Aztec culture ( /ˈæztɛk/  ), also known as Mexica culture, was a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521, during the time in which a triple alliance of the Mexica, Texcoca and Tepaneca tribes established the Aztec empire. The Aztec people were certain ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica from the 14th to the 16th centuries. The Aztec have also referred to themselves as the Meshika or Mehika. 
Aztec culture is the culture of the people referred to as Aztecs, but since most ethnic groups of central Mexico in the postclassic period shared basic cultural traits, many of the traits that characterize Aztec culture cannot be said to be exclusive to the Aztecs. For the same reason, the notion of "Aztec civilization" is best understood as a particular horizon of a general Mesoamerican civilization. The culture of central Mexico includes maize cultivation, the social division between pipiltin nobility and macehualtin commoners, a pantheon (featuring Tezcatlipoca, Tlaloc and Quetzalcoatl), and the calendric system of a xiuhpohualli of 365 days intercalated with a tonalpohualli of 260 days. Particular to the Aztecs of Tenochtitlan was the Mexica patron God Huitzilopochtli, twin pyramids, and the ceramic ware known as Aztec I to III.
From the 13th century, the Valley of Mexico was the heart of Aztec civilization: there the city of Tenochtitlan, the capital of the Aztec Triple Alliance, was built upon raised islets in Lake Texcoco. The Triple Alliance formed the Aztec Empire, a tributary empire that expanded its political hegemony far beyond the Valley of Mexico, conquering other city states throughout Mesoamerica in the late postclassic period. It originated in 1427 as an alliance between the city-states Tenochtitlan, Texcoco, and Tlacopan ; these allied to defeat the Tepanec state of Azcapotzalco, which had previously dominated the Basin of Mexico. Soon Texcoco and Tlacopan became junior partners in the alliance, of which the Mexica of Tenochtitlan were the de facto leaders. The empire extended its power by a combination of trade and military conquest. It was never a true territorial empire controlling a territory by large military garrisons in conquered provinces, but rather controlled its client states primarily by installing friendly rulers in conquered cities, by constructing marriage alliances between the ruling dynasties, and by extending an imperial ideology to its client states. Client states paid tribute to the Aztec emperor, the Huey Tlatoani, in an economic strategy limiting communication and trade between outlying polities, making them dependent on the imperial center for the acquisition of luxury goods. The political clout of the empire reached far south into Mesoamerica conquering cities as far south as Chiapas and Guatemala and spanning from the Pacific to the Atlantic oceans. The empire reached its maximal extent in 1519, just prior to the arrival of the Spanish conquistadors led by Hernán Cortés, who managed to topple the Aztec empire by allying with some of the traditional enemies of the Aztecs, the Nahuatl-speaking Tlaxcalteca. Subsequently, the Spanish founded the new settlement of Mexico City on the site of the ruined Aztec capital, from where they proceeded with the process of colonizing Central America.
Aztec culture and history is primarily known through archaeological evidence found in excavations such as that of the renowned Templo Mayor in Mexico City; from indigenous bark paper codices ; from eyewitness accounts by Spanish conquistadors such as Cortés and Bernal Díaz del Castillo ; and especially from 16th- and 17th-century descriptions of Aztec culture and history written by Spanish clergymen and literate Aztecs in the Spanish or Nahuatl language, such as the famous Florentine Codex compiled by the Franciscan monk Bernardino de Sahagún with the help of indigenous Aztec informants. At its height, Aztec culture had rich and complex mythological and religious traditions, as well as achieving remarkable architectural and artistic accomplishments.
The Nahuatl words aztecatl [asˈtekat͡ɬ] (singular)  and aztecah [asˈtekaʔ] ( plural)  mean "people from Aztlan ",  a mythological place for the Nahuatl-speaking culture of the time, and later adopted as the word to define the Mexica people. Often the term "Aztec" refers exclusively to the Mexica people of Tenochtitlan (now the location of Mexico City), situated on an island in Lake Texcoco, who referred to themselves as Mēxihcah Tenochcah [meːˈʃiʔkaʔ teˈnot͡ʃkaʔ] or Cōlhuah Mexihcah [ˈkoːlwaʔ meːˈʃiʔkaʔ] .
Sometimes the term also includes the inhabitants of Tenochtitlan's two principal allied city-states, the Acolhuas of Texcoco and the Tepanecs of Tlacopan, who together with the Mexica formed the Aztec Triple Alliance that controlled what is often known as the "Aztec Empire". In other contexts, Aztec may refer to all the various city states and their peoples, who shared large parts of their ethnic history and cultural traits with the Mexica, Acolhua and Tepanecs, and who often also used the Nahuatl language as a lingua franca. In this meaning, it is possible to talk about an Aztec civilization including all the particular cultural patterns common for most of the peoples inhabiting central Mexico in the late postclassic period.
When used to describe ethnic groups, the term "Aztec" refers to several Nahuatl-speaking peoples of central Mexico in the postclassic period of Mesoamerican chronology, especially the Mexica, the ethnic group that had a leading role in establishing the hegemonic empire based at Tenochtitlan. The term extends to further ethnic groups associated with the Aztec empire, such as the Acolhua, the Tepanec and others that were incorporated into the empire. In older usage the term was commonly used about modern Nahuatl-speaking ethnic groups, as Nahuatl was previously referred to as the "Aztec language". In recent usage, these ethnic groups are referred to as the Nahua peoples. Linguistically, the term "Aztecan" is still used about the branch of the Uto-Aztecan languages (also sometimes called the yuto-nahuan languages) that includes the Nahuatl language and its closest relatives Pochutec and Pipil. 
To the Aztecs themselves the word "aztec" was not an endonym for any particular ethnic group. Rather, it was an umbrella term used to refer to several ethnic groups, not all of them Nahuatl-speaking, that claimed heritage from the mythic place of origin, Aztlan. In the Nahuatl language " aztecatl " means "person from Aztlan". Alexander von Humboldt originated the modern usage of "Aztec" in 1810, as a collective term applied to all the people linked by trade, custom, religion, and language to the Mexica state and the Triple Alliance. In 1843, with the publication of the work of William H. Prescott, the term was adopted by most of the world, including 19th-century Mexican scholars who saw it as a way to distinguish present-day Mexicans from pre-conquest Mexicans. This usage has been the subject of debate in more recent years, but the term "Aztec" is still more common.
Central Mexico in the classic and post-classic
It is a matter of debate whether the enormous city of Teotihuacan was inhabited by speakers of Nahuatl, or whether Nahuas had not yet arrived in central Mexico in the classic period. It is generally agreed that the Nahua peoples were not indigenous to the highlands of central Mexico, but that they gradually migrated into the region from somewhere in northwestern Mexico. At the fall of Teotihuacan in the 6th century CE, a number of city states rose to power in central Mexico, some of them, including Cholula and Xochicalco, probably inhabited by Nahuatl speakers. One study has suggested that Nahuas originally inhabited the Bajío area around Guanajuato which reached a population peak in the 6th century, after which the population quickly diminished during a subsequent dry period. This depopulation of the Bajío coincided with an incursion of new populations into the Valley of Mexico, which suggests that this marks the influx of Nahuatl speakers into the region. These populated central Mexico, dislocating speakers of Oto-Manguean languages as they spread their political influence south. As the former nomadic hunter-gatherer peoples mixed with the complex civilizations of Mesoamerica, adopting religious and cultural practices, the foundation for later Aztec culture was laid. After 900 CE, during the Postclassic period, a number of sites almost certainly inhabited by Nahuatl speakers became powerful. Among them the site of Tula, Hidalgo, and also city states such as Tenayuca, and Colhuacan in the valley of Mexico and Cuauhnahuac in Morelos.
Migrational period and foundation of Tenochtitlan
In the ethnohistorical sources from the colonial colonial period, Aztecs themselves describe their arrival in the Valley of Mexico. The ethnonym Aztec (Nahuatl ‘‘Aztecah’’) means “people from Aztlan ”, Aztlan being a mythical place of origin toward the north. Hence the term applied to all those peoples who claimed to carry the heritage from this mythical place. The migration stories of the Mexica tribe tell how they traveled with other tribes, including the Tlaxcalteca, Tepaneca and Acolhua, but that eventually their tribal deity Huitzilopochtli told them to split from the other Aztec tribes and take on the name “Mexica”. At the time of their arrival, there were many Aztec city-states in the region. The most powerful were Colhuacan to the south and Azcapotzalco to the west. The Tepanecs of Azcapotzalco soon expelled the Mexicas from Chapultepec. In 1299, Colhuacan ruler Cocoxtli gave them permission to settle in the empty barrens of Tizapan, where they were eventually assimilated into Culhuacan culture. The noble lineage of Colhuacan traced its roots back to the legendary city state of Tula, and by marrying into Colhua families the Mexica now also adopted this heritage. After living in Colhuacan the Mexica were again expelled and moved on. According to Aztec legend, in 1323 the Mexicas were shown a vision of an eagle perched on a prickly pear cactus, eating a snake. The vision indicated the location where they were to build their home. The Mexica founded the town of Tenochtitlan on a small swampy island in Lake Texcoco. The year of foundation is usually given as 1325. In 1376 the Mexica royal dynasty was founded when Acamapichtli, son of a Mexica father and a Colhua mother, was elected as the first ‘’ Huey Tlatoani ’’ of Tenochtitlan.
In the first 50 years after the founding of the Mexica dynasty, the Mexica were a tributary of Azcapotzalco, which had become a major regional power under the ruler Tezozomoc. The Mexica supplied the Tepaneca with warriors for their successful conquest campaigns in the region and received part of the tribute from the conquered city states. In this way, the prestige and economy of Tenochtitlan gradually grew.
In 1396, at Acamapichtli’s death, his son Huitzilihhuitl (Nahuatl: "Hummingbird feather") became ruler, married to Tezozomoc’s daughter the relation with Azcapotzalco remained close. Chimalpopoca (Nahuatl: "She smokes like a shield"), son of Huitzilihhuitl, became ruler of Tenochtitlan in 1417. In 1418, Azcapotzalco initiated a war against the Acolhua of Texcoco, and killed their ruler Ixtlilxochitl. Even though Ixtlilxochitl was married to Chimalpopoca’s daughter, the Mexica ruler continued to support Tezozomoc. Tezozomoc died in 1426, and his sons began a struggle for rulership of Azcapotzalco. During this struggle for power Chimalpopoca died, probably killed by Tezozomoc’s son Maxtla who saw him as a competitor.
Itzcoatl brother of Huitzilihhuitl and uncle of Chimalpopoca, was elected the next Mexica tlatoani. The Mexica were now in open war with Azcapotzalco and Itzcoatl petitioned for an alliance with Nezahualcoyotl, son of the slain Texcocan ruler Ixtlilxochitl against Maxtla. Itzcoatl also allied with Maxtla’s brother Totoquihuaztli ruler of the Tepanec city of Tlacopan. The Triple Alliance of Tenochtitlan, Texcoco and Tlacopan besieged Azcapotzalco, and in 1428 they destroyed the city and sacrificed Maxtla. Through this victory Tenochtitlan became the dominant city state in the Valley of Mexico, and the alliance between the three cities provided the basis on which the Aztec Empire was built.
Itzcoatl proceeded by securing a power basis for Tenochtitlan, by conquering the city-states on the southern lake – including Colhuacan, Xochimilco, Cuitlahuac and Mizquic. These states had an economy based on highly productive chinampa agriculture, cultivating floating gardens in the shallow lake Xochimilco. Itzcoatl then undertook further conquests in the valley of Morelos, subjecting the city state of Cuauhnahuac (today Cuernavaca).
Motecuzoma I Ilhuicamina
In 1440, Motecuzoma I Ilhuicamina (Nahuatl: "he frowns like a lord, he shoots the sky"  was elected tlatoani, he was son of Huitzilihhuitl, brother of Chimalpopoca and had served as the war leader of his uncle Itzcoatl in the war against the Tepanecs. The accession of a new ruler in the dominant city state was often an occasion for subjected cities to rebel by refusing to pay tribute. This meant that new rulers began their rule with a coronation campaign, often against rebellious tributaries, but also sometimes demonstrating their military might by making new conquests. Motecuzoma tested the attitudes of the cities around the valley by requesting laborers for the enlargement of the Great Temple of Tenochtitlan. Only the city of Chalco refused to provide laborers, and hostilities between Chalco and Tenochtitlan would persist until the 1450s. Motecuzoma then reconquered the cities in the valley of Morelos and Guerrero, and then later undertook new conquests in the Huaxtec region of northern Veracruz, and the Mixtec region of Coixtlahuaca and large parts of Oaxaca, and later again in central and southern Veracruz with conquests at Cosamalopan, Ahuilizapan and Cuetlaxtlan. During this period the city states of Tlaxcallan, Cholula and Huexotzinco emerged as major competitors to the imperial expansion, and they supplied warriors to several of the cities conquered. Motecuzoma therefore initiated a state of low intensity warfare against these three cities, staging minor skirmishes called “Flower Wars” (Nahuatl ‘’xochiyaoyotl’’) against them, perhaps as a strategy of exhaustion.
Motecuzoma also consolidated the political structure of the Triple Alliance, and the internal political organization of Tenochtitlan. His brother Tlacaelel served as his main advisor (Nahuatl ‘’Cihuacoatl’’) and he is considered the architect of major political reforms in this period, consolidating the power of the noble class (Nahuatl ‘’pipiltin’’) and instituting a set of legal codes, and the practice of reinstating conquered rulers in their cities bound by fealty to the Mexica tlatoani.
Axayacatl and Tizoc
In 1469, the next ruler became Axayacatl (Nahuatl: "Water mask"), son of Itzcoatl’s son Tezozomoc and Motecuzoma I’s daughter Atotoztli.  He undertook a successful coronation campaign far south of Tenochtitlan against the Zapotecs in the Isthmus of Tehuantepec. Axayacatl also conquered the independent Mexica city of Tlatelolco, located on the northern part of the island where Tenochtitlan was also located. The Tlatelolca ruler Moquihuix was married to Axayacatl’s sister, and his alleged mistreatment of her was used as an excuse to incorporate Tlatelolco and its important market directly under the control of the tlatoani of Tenochtitlan.
Axayacatl then conquered areas in Central Guerrero, the Puebla Valley, on the gulf coast and against the Otomi and Matlatzinca in the Toluca valley. The Toluca valley was a buffer zone against the powerful Tarascan state in Michoacan, against which Axayacatl turned next. In the major campaign against the Tarascans (Nahua ‘’Michhuahqueh’’) in 1478–79 the Aztec forces were repelled by a well organized defense. Axayacatl was soundly defeated in a battle at Tlaximaloyan (today Tajimaroa), losing most of his 32,000 men and only barely escaping back to Tenochtitlan with the remnants of his army.
In 1481 at Axayacatls death, his older brother Tizoc was elected ruler. Tizoc’s coronation campaign against the Otomi of Metztitlan failed as he lost the major battle and only managed to secure 40 prisoners to be sacrificed for his coronation ceremony. Having shown weakness, many of the tributary towns rebelled and consequently most of Tizoc’s short reign was spent attempting to quell rebellions and maintain control of areas conquered by his predecessors. Tizoc died suddenly in 1485, and it has been suggested that he was poisoned by his brother and war leader Ahuitzotl who became the next tlatoani. Tizoc is mostly known as the namesake of the Stone of Tizoc a monumental sculpture (Nahuatl ‘’temalacatl’’), decorated with representation of Tizoc’s conquests.
The next ruler was Ahuitzotl (Nahuatl: "Water monster"), brother of Axayacatl and Tizoc and war leader under Tizoc. His successful coronation campaign suppressed rebellions in the Toluca valley and conquered Jilotepec and several communities in the northern Valley of Mexico. A second campaign to the gulf coast was also highly successful. He began an enlargement of the Great Temple of Tenochtitlan, inaugurating the new temple in 1487. For the inauguration ceremony the Mexica invited the rulers of all their subject cities, who participated as spectators in the ceremony in which an unprecedented number of war captives were sacrificed – some sources giving a figure of 84,000 prisoners sacrificed over four days. Probably the actual figure of sacrifices was much smaller, but still numbering several thousands. Ahuitzotl also constructed monumental architecture in sites such as Calixtlahuaca, Malinalco and Tepoztlan. After a rebellion in the towns of Alahuiztlan and Oztoticpac in Northern Guerrero he ordered the entire population executed, and repopulated with people from the valley of Mexico. He also constructed a fortified garrison at Oztuma defending the border against the Tarascan state.
Motecuzoma II Xocoyotzin
At the death of Ahuitzotl the reign passed to his war leader Motecuzoma Xocoyotzin (Nahuatl "He frowns like a lord, the youngest child"), a son of Axayacatl. His successful coronation campaign attacked the fortified city of Nopallan in Oaxaca and subjected the adjacent region to the empire. An effective warrior, Motecuzoma II maintained the pace of conquest set by his predecessor and subjected large areas in Guerrero, Oaxaca, Puebla and even far south along the Pacific and Gulf coasts, conquering the province of Xoconochco in Chiapas. he also intensified the flower wars waged against Tlaxcallan and Huexotzinco, and secured an alliance with Cholula. He also consolidated the class structure of Aztec society, by making it harder for commoners (Nahuatl macehualtin ) to accede to the privileged class of the pipiltin through merit in combat, and instituted a strict sumptuary code limiting the types of luxury goods that could be consumed by commoners.
In 1517, Motecuzoma received the first news of ships with strange warriors having landed on the Gulf Coast near Cempoallan and he dispatched messengers to greet them and find out what was happening, and he ordered his subjects in the area to keep him informed of any new arrivals. In 1519, he was informed of the arrival of the Spanish fleet of Hernán Cortés, who soon marched towards Tlaxcallan where he formed an alliance with the traditional enemies of the Aztecs. On November 8, 1519, Motecuzoma II received Cortés and his troops and Tlaxcalan allies on the causeway south of Tenochtitlan, and he invited the Spaniards to stay as his guests in Tenochtitlan. When Aztec troops destroyed a Spanish camp on the gulf coast, Cortés ordered Motecuzoma to execute the commanders responsible for the attack, and Motecuzoma complied. At this point the power balance had shifted towards the Spaniards who now held Motecuzoma as a prisoner in his own palace. As this shift in power became clear to Motecuzoma's subjects the Spaniards became increasingly unwelcome guests in the capital city, and in June 1520, hostilities broke out, culminating in the massacre in the Great Temple, and a major uprising of the Mexica against the Spanish. During the fighting Motecuzoma was killed, either by the Spaniards who killed him as they fled the city or by the Mexica themselves who considered him a traitor.
The Spaniards fled the town on July 1, an episode later characterized as La Noche Triste (the Sad Night), which was a major victory for the Aztecs. The Spaniards nevertheless reached Tlaxcallan where they regrouped and received reinforcements, and began to prepare a campaign of conquest in collaboration with the Tlaxcalteca. In Tenochtitlan a new tlatoani was chosen, Motecuzoma's brother Cuitlahuac, but as an epidemic of smallpox swept through the city he died having ruled less than a year. At his death Cuauhtemoc, son of Ahuitzotl was elected tlahtoani. The Spaniards and thousands of Tlaxcalteca allies returned in the spring of 1521 to lay siege to Tenochtitlan, beginning by conquering the altepetl on the lake bank, cutting off communications and provisions to the island. They then besieged the island of Tenochtitlan from the land side, also attacking from the lakeside with ships built for the purpose. The battle ended on August 13 with the destruction of the city, and the imprisonment of Cuauhtemoc, who was later executed along with the rulers of Tlacopan and Texcoco.
After the fall of Tenochtitlan, Aztec warriors were enlisted as auxiliary troops alongside the Spanish Tlaxcalteca allies, and Aztec forces participated in all of the subsequent campaigns of conquest in northern and southern Mesoamerica. This meant that aspects of Aztec culture and the Nahuatl language continued to expand during the early colonial period as Aztec auxiliary forces made permanent settlements in many of the areas that were put under the Spanish crown.
During the colonial period the Aztec ruling dynasty continued to govern the "indian republic" of Tenochtitlan, but the subsequent rulers were mostly puppets installed by the Spanish, such as Andrés de Tapia Motelchiuh, installed by the Spanish. Other Aztec city states likewise came to be governed as "Indian republics" with a local indigenous gobernador in charge of the political organization of the Indians, and of providing the Spanish landowners with tribute and corvee labor. Some indigenous governors became quite rich and influential and were able to maintain positions of power comparable to that of Spanish encomenderos.
Colonial period population decline
After the arrival of the Europeans in Mexico and the conquest, indigenous populations plummeted. This was largely the result of the epidemics of viruses brought to the continent against which the natives had no immunity.
In 1520–1521, an outbreak of smallpox swept through the population of Tenochtitlan and was decisive in the fall of the city. It is estimated that between 10% and 50% of the population fell victim to this epidemic.
Subsequently, the Valley of Mexico was hit with two more epidemics, smallpox (1545–1548), and typhus (1576–1581). The Spaniards, to consolidate the diminishing population, merged the survivors from small towns in the Valley of Mexico into bigger ones. This broke the power of the upper classes, but did not dissolve the coherence of the indigenous society in greater Mexico.
The population before the time of the conquest is unknown and hotly contested, but disease is known to have ravaged the region; thus, the indigenous population of the Valley of Mexico is estimated to have declined by more than 80% in the course of about 60 years. 
Political and social organization
Nobles and commoners
The highest class were the pīpiltin or nobility. The pilli status was hereditary and ascribed certain privileges to its holder, such as the right to wear particularly fine garments and consume luxury goods, as well as to own land and direct corvée labor by commoners. The most powerful nobles were called lords (Nahuatl teuctin ) and they owned and controlled noble estates or houses, and could serve in the highest government positions or as military leaders. Nobles made up about 5% of the population. p= The second class were the mācehualtin , originally peasants, but later extended to the lower working classes in general. Eduardo Noguera estimates that in later stages only 20% of the population was dedicated to agriculture and food production. The other 80% of society were warriors, artisans and traders. Eventually, most of the mācehuallis were dedicated to arts and crafts. Their works were an important source of income for the city. Macehualtin could become enslaved, (Nahuatl tlacotin ) for example if they had to sell themselves into the service of a noble due to debt or poverty, but enslavement was not an inherited status among the Aztecs. Some macehualtin were landless and worked directly for a lord (Nahuatl mayehqueh ), whereas the majority of commoners were organized into calpollis which gave them access to land and property.
Commoners were able to obtain privileges similar to those of the nobles by demonstrating prowess in warfare. When a warrior took a captive he accrued the right to use certain emblems, weapons or garments, and as he took more captives his rank and prestige increased.
Family and gender
The Aztec family pattern was bilateral, counting relatives on the fathers and mothers side of the family equally, and inheritance was also passed both to sons and daughters. This meant that women could own property just as men, and that women therefore had a good deal of economic freedom from their spouses. Nevertheless, Aztec society was highly gendered with separate gender roles for men and women. Men were expected to work outside of the house, as farmers, traders, craftsmen and warriors, whereas women were expected to take the responsibility of the domestic sphere. Women could however also work outside of the home as small-scale merchants, doctors, priests and midwives. Warfare was highly valued and a source of high prestige, but women's work was metaphorically conceived of as equivalent to warfare, and as equally important in maintaining the equilibrium of the world and pleasing the gods. This situation has led some scholars to describe Aztec gender ideology as an ideology not of a gender hierarchy, but of gender complementarity, with gender roles being separate but equal.
Among the nobles, marriage alliances were often used as a political strategy with lesser nobles marrying daughters from more prestigious lineages whose status was then inherited by their children. Nobles were also often polygamous, with lords having many wives. Polygamy was not very common among the commoners and some sources describe it as being prohibited.
Altepetl and calpolli
The main unit of Aztec political organization was the city state, in Nahuatl called the altepetl , meaning "water-mountain". Each altepetl was lead by a ruler, a tlatoani , with authority over a group of nobles and a population of commoners. The altepetl included a capital which served as a religious center, the hub of distribution and organization of a local population which often lived spread out in minor settlements surrounding the capital. Altepetl were also the main source of ethnic identity for the inhabitants, even though Altepetl were frequently composed of groups speaking different languages. Each altepetl would see itself as standing in a political contrast to other altepetl states, and war was waged between altepetl states. In this way Nahuatl speaking Aztecs of one AAltepetl would be solidary with speakers of other languages belonging to the same altepetl, but enemies of Nahuatl speakers belonging to other competing altepetl states. In the valley of Mexico altepetl was composed of subdivisions called calpolli , which served as the main organizational unit for commoners. In Tlaxcala and the Puebla valley, the altepetl was organized into teccalli units headed by a lord (Nahuatl tecuhtli ), who would hold sway over a territory and distribute rights to land among the commoners. A calpolli was at once a territorial unit where commoners organized labor and land use, since land was not in private property, and also often a kinship unit as a network of families that were related through intermarriage. Calpolli leaders might be or become members of the nobility, in which case they could represent their calpollis interests in the altepetl government.
In the valley of Morelos, Michael E. Smith estimates that a typical altepetl had from 10,000 to 15,000 inhabitants, and covered an area between 70 and 100 square kilometers. In the Morelos valley altepetl sizes were somewhat smaller. Smith argues that the altepetl was primarily a political unit, made up of the population with allegiance to a lord, rather than as a territorial unit. He makes this distinction because in some areas minor settlements with different altepetl allegiances were interspersed.
The Aztec Empire was ruled by indirect means. Like most European empires, it was ethnically very diverse, but unlike most European empires, it was more of a system of tribute than a single system of government. In the theoretical framework of imperial systems posited by Alexander J. Motyl, the Aztec empire was an informal or hegemonic empire because it did not exert supreme authority over the conquered lands; it merely expected tributes to be paid. It was also a discontinuous empire because not all dominated territories were connected; for example, the southern peripheral zones of Xoconochco were not in direct contact with the center. The hegemonic nature of the Aztec empire can be seen in the fact that generally local rulers were restored to their positions once their city-state was conquered, and the Aztecs did not interfere in local affairs as long as the tribute payments were made.
Although the form of government is often referred to as an empire, in fact most areas within the empire were organized as city-states, known as altepetl in Nahuatl. These were small polities ruled by a king (tlatoani) from a legitimate dynasty. The Early Aztec period was a time of growth and competition among altepetl. Even after the empire was formed in 1428 and began its program of expansion through conquest, the altepetl remained the dominant form of organization at the local level. The efficient role of the altepetl as a regional political unit was largely responsible for the success of the empire's hegemonic form of control.
Agriculture and subsistence
As all Mesoamerican peoples Aztec society was organized around maize agriculture. The humid environment in the Valley of Mexico with its many lakes and swamps permitted intensive agriculture. The main crops in addition to maize were beans, squashes, chilies and amaranth. Particularly important for agricultural production in the valley was the construction of chinampas on the lake, artificial islands that allowed the conversion of the shallow waters into highly fertile gardens that could be cultivated year round. Chinampas are areas of raised land, created from alternating layers of mud from the bottom of the lake, and plant matter/other vegetation. These “raised beds” were separated by narrow canals, which allowed farmers to move between them by canoe. The chinampas were extremely fertile pieces of land, and yielded, on average, seven crops annually. On the basis of current chinampa yields, it has been estimated that 1 hectare of chinampa would feed 20 individuals and 9,000 hectares of chinampas could feed 180,000. 
The Aztecs further intensified agricultural production by constructing systems of artificial irrigation. While most of the farming occurred outside the densely populated areas, within the cities there was another method of (small scale) farming. Each family had their own garden plot where they grew maize, fruits, herbs, medicines and other important plants. When the city of Tenochtitlan became a major urban center, water was supplied to the city through aqueducts from springs on the banks of the lake, and they organized a system that collected human waste for use as fertilizer. Through intensive agriculture the Aztecs were able to sustain a large urbanized population. The lake was also a rich source of proteins in the form of aquatic animals such as fish, amphibians, shrimp, insects and insect eggs, and water fowl. The presence of such varied sources of protein meant that there was little use for domestic animals for meat (only turkeys and dogs were kept), and scholars have calculated that there was no shortage of protein among the inhabitants of the Valley of Mexico.
Crafts and trades
The excess supply of food products allowed a significant portion of the Aztec population to dedicate themselves to trades other than food production. Apart from taking care of domestic food production women weaved textiles from agave fibers and cotton. Men also engaged in craft specializations such as the production of ceramics and of obsidian and flint tools, and of luxury goods such as beadwork, featherwork and the elaboration of tools and musical instruments. Sometimes entire calpollis specialized in a single craft, and in some archeological sites large neighborhoods have been found where apparently only a single craft speciality was practiced.
The Aztecs did not produce much metal work, but did have knowledge of basic smelting technology for gold, and they combined gold with precious stones such as jade and turquoise. Copper products were generally imported from the Tarascans of Michoacan.
Trade and distribution
Products were distributed through a network of markets; some markets specialized in a single commodity (for example the dog market of Acolman) and other general markets with presence of many different goods. Markets were highly organized with a system of supervisors taking care that only authorized merchants were permitted to sell their goods, and punishing those who cheated their customers or sold substandard or counterfeit goods. A typical town would have a weekly market (every 5 days), while larger cities held markets every day. Cortés reported that the central market of Tlatelolco, Tenochtitlan's sister city, was visited by 60,000 people daily. Some sellers in the markets were petty vendors; farmers might sell some of their produce, potters sold their vessels, and so on. Other vendors were professional merchants who traveled from market to market seeking profits.
The pochteca were specialized long distance merchants organized into exclusive guilds. They made long expeditions to all parts of Mesoamerica bringing back exotic luxury goods, and they served as the judges and supervisors of the Tlatelolco market. Although the economy of Aztec Mexico was commercialized (in its use of money, markets, and merchants) land and labor were not commodities for sale. In the commercial sector of the economy several types of money were in regular use. Small purchases were made with cacao beans, which had to be imported from lowland areas. In Aztec marketplaces, a small rabbit was worth 30 beans, a turkey egg cost 3 beans, and a tamal cost a single bean. For larger purchases, standardized lengths of cotton cloth called quachtli were used. There were different grades of quachtli, ranging in value from 65 to 300 cacao beans. One source stated that 20 quachtli could support a commoner for one year in Tenochtitlan. A man could also sell his own daughter as a sexual slave or future religious sacrifice, generally for around 500 to 700 beans. A small gold statue approximately 0.62 kg (1.37 lb) cost 250 beans.
Another form of distribution of goods was through the payment of tribute. When an altepetl was conquered the victor imposed a yearly tribute, usually paid in the form of whichever local product was most valuable or treasured. Several pages from the Codex Mendoza list tributary towns along with the goods they supplied, which included not only luxuries such as feathers, adorned suits, and greenstone beads, but more practical goods such as cloth, firewood, and food. Tribute was usually paid twice or four times a year at differing times.
Archaeological excavations in the Aztec-ruled provinces show that incorporation into the empire had both costs and benefits for provincial peoples. On the positive side, the empire promoted commerce and trade, and exotic goods from obsidian to bronze managed to reach the houses of both commoners and nobles. Trade partners also included the enemy Purépecha (also known as Tarascans), a source of bronze tools and jewelry. On the negative side, imperial tribute imposed a burden on commoner households, who had to increase their work to pay their share of tribute. Nobles, on the other hand, often made out well under imperial rule because of the indirect nature of imperial organization. The empire had to rely on local kings and nobles and offered them privileges for their help in maintaining order and keeping the tribute flowing.
Aztec society was a combined a relatively simple agrarian rural tradition with the development of truly urbanized society with a complex system of institutions, specializations and hierarchies. The urban tradition in Mesoamerica was developed during the classic period with major urban centers such as Teotihuacan with a population well above 100,000, and at the rise of the Aztec the urban tradition was ingrained in Mesoamerican society, with urban centers serving major religious, political and economic functions for the entire population.
The capital city of the Aztec empire was Tenochtitlan, now the site of modern-day Mexico City. Built on a series of islets in Lake Texcoco, the city plan was based on a symmetrical layout that was divided into four city sections called campan (directions). Tenochtitlan was built according to a fixed plan and centered on the ritual precinct, where the Great Pyramid of Tenochtitlan rose 50 m (164.04 ft) above the city. Houses were made of wood and loam, roofs were made of reed, although pyramids, temples and palaces were generally made of stone. The city was interlaced with canals, which were useful for transportation. Anthropologist Eduardo Noguera estimates the population at 200,000 based in the house count and merging the population of Tlatelolco (once an independent city, but later became a suburb of Tenochtitlan). If one includes the surrounding islets and shores surrounding Lake Texcoco, estimates range from 300,000 to 700,000 inhabitants.  Michael E. Smith gives a somewhat smaller figure of 212,500 inhabitants of Tenochtitlan based on an area of 1,350 hectares and a population density of 157. The second largest city in the valley of Mexico in the Aztec period was texcoco with some 25,000 inhabitants dispersed over 450 hectares.
The center of Tenochtitlan was the sacred precinct, a walled-off square area which housed the Great Temple, temples for other deities, the ballcourt, the calmecac (a school for nobles), a skull rack ‘’tzompantli’’, displaying the skulls of sacrificial victims, houses of the warrior orders, a penitential palace of the tlatoani and a merchants palace. Around the sacred precinct were the royal palaces of the rulers.
The Great Temple
The centerpiece of Tenochtitlan was the Templo Mayor, the Great Temple, a large stepped pyramid with a double stair case leading up to two twin shrines – one dedicated to Tlaloc the other to Huitzilopochtli. This was where most of the human sacrifices were carried out during the ritual festivals and the bodies of sacrificial victims were thrown down the stairs. The temple was enlarged in several stages, and most of the Aztec rulers made a point of adding a further stage, each with a new dedication and inauguration. The temple has been excavated in the center of Mexico City and the rich dedicatory offerings are displayed in the Museum of the Templo Mayor.
Archaeologist Eduardo Matos Moctezuma, in his essay "Symbolism of the Templo Mayor," posits that the orientation of the temple is indicative of the totality of the vision the Mexica had of the universe ( cosmovision). He states that the "principal center, or navel, where the horizontal and vertical planes intersect, that is, the point from which the heavenly or upper plane and the plane of the Underworld begin and the four directions of the universe originate, is the Templo Mayor of Tenochtitlan." Matos Moctezuma supports his supposition by claiming that the temple acts as an embodiment of a living myth where "all sacred power is concentrated and where all the levels intersect."
Other major Aztec cities were some of the previous city state centers around the lake including Tenayuca, Azcapotzalco, Texcoco, Colhuacan, Tlacopan, Chapultepec, Coyoacan, Xochimilco, and Chalco. In the Puebla valley Cholula was the largest city with the largest pyramid temple in Mesoamerica, while the confederacy of Tlaxcala consisted of four smaller cities. In Morelos, Cuahnahuac was a major city of the Nahuatl speaking Tlahuica tribe, and Tollocan in the Toluca valley was the capital of the Matlatzinca tribe which included Nahuatl speakers as well as speakers of Otomi and the language today called Matlatzinca. Most Aztec cities had a similar layout with a central plaza with a major pyramid with two staircases and a double temple oriented towards the west.
Aztec religion was organized around the practice of calendar rituals dedicated to a pantheon of different deities. Similar to other Mesoamerican religious systems it has generally been understood as a polytheist agriculturalist religion with elements of animism. Central in the religious practice was the offering of sacrifices to the deities, as a way of thanking or paying for the continuation of the cycle of life.
The main deities worshipped by the Aztecs were Tlaloc, a rain and storm deity, Huitzilopochtli a solar and martial deity and the tutelary deity of the Mexica tribe, Quetzalcoatl, a wind, sky and star deity and cultural hero, Tezcatlipoca, a deity of the night, magic, prophecy and fate. The Great Temple in Tenochtitlan had two shrines on its top, one dedicated to Tlaloc, the other to Huitzilopochtli. Quetzalcoatl and Tezcatlipoca each had separate temples within the religious precinct close to the Great Temple, and the high priests of the Great Temple were named “’’Quetzalcoatl Tlamacazqueh’’”. Other major deities were Tlaltecutli or Coatlicue a female earth deity, the deity couple Tonacatecuhtli and Tonacacihuatl were associated with life and sustenance, Mictlantecutli and Mictlancihuatl, a male/female couple of deities of the underworld and death, Chalchiutlicue, a female deity of lakes and springs, Xipe Totec, a deity of fertility and the natural cycle, Huehueteotl or Xiuhtecuhtli a fire god, Tlazolteotl a femal deity tied to childbirth and sexuality, and a Xochipilli and Xochiquetzal gods of song, dance and games. In some regions, particularly Tlaxcala, Mixcoatl or Camaxtli was the main tribal deity. A few sources mention a deity Ometeotl who may have been a god of the duality between life and death, male and female and who may have incorporated Tonacatecuhtli and Tonacacihuatl. Apart from the major deities there were dozens of minor deities each associated with an element or concept, and as the Aztec empire grew so did their pantheon because they adopted and incorporated the local deities of conquered people into their own. Additionally the major gods had many alternative manifestations or aspects, creating small families of gods with related aspects.
Mythology and Cosmovision
Aztec mythology is known from a number of sources written down in the colonial period. One set of myths, called Legend of the Suns, describe the creation of four successive suns, or periods, each ruled by a different deity and inhabited by a different group of beings. Each period ends in a cataclysmic destruction that sets the stage for the next period to begin. In this process, the deities Tezcatlipoca and Quetzalcoatl appear as adversaries, each destroying the creations of the other. The current Sun, the fifth, was created when a minor deity sacrificed himself on a bonfire and turned into the sun, but the sun only begins to move once the other deities sacrifice themselves and offers it their life force.
In another myth of how the earth was created Tezcatlipoca and Quetzalcoatl appear as allies, defeating a giant crocodile Cipactli and requiring her to become the earth, allowing humans to carve into her flesh and plant their seeds, on the condition that in return they will offer blood to her. And in the story of the creation of humanity Quetzalcoatl travels with his twin Xolotl to the underworld and brings back bones which are then ground like corn on a metate by the goddess Cihuacoatl, the resulting dough is given human form and comes to life when Quetzalcoatl imbues it with his own blood.
Huitzilopochtli is the deity tied to the Mexica tribe and he figures in the story of the origin and migrations of the tribe. On their journey, Huitzilopochtli, in the form of a deity bundle carried by the Mexica priest, continuously spurs the tribe on by pushing them into conflict with their neighbors whenever they are settled in a place. In another myth Huitzilopochtli defeats and dismembers his sister the lunar deity Coyolxauhqui and her four hundred brothers at the hill of Coatepetl. The southern side of the Great Temple, also called Coatepetl, was a representation of this myth and at the food of the stairs lay a large stone monolith carved with a representation of the dismembered goddess.
Aztec religious life was organized around the calendars. As most Mesoamerican people, the Aztecs used two calendars simultaneously: a ritual calendar of 260 days called the tonalpohualli and a solar calendar of 365 days called the xiuhpohualli. Each day had a name and number in both calendars, and the combination of two dates were unique within a period of 52 years. The tonalpohualli was mostly used for divinatory purposes and it consisted of 20 day signs and number coefficients of 1–13 that cycled in a fixed order. The xiuhpohualli was made up of 18 “months” of 20 days, and with a remainder of 5 “void” days at the end of a cycle before the new xiuhpohualli cycle began. Each 20-day month was named after the specific ritual festival that began the month, many of which contained a relation to the agricultural cycle. Whether, and how, the Aztec calendar corrected for leap year is a matter of discussion among specialists. The monthly rituals involved the entire population as rituals were performed in each household, in the calpolli temples and in the main sacred precinct. Many festivals involved different forms of dancing, as well as the reenactment of mythical narratives by deity impersonators and the offering of sacrifice, in the form of food, animals and human victims.
Every 52 years the two calendars reached their shared starting point and a new calendar cycle began. This calendar event was celebrated with a ritual known as Xiuhmolpilli or the New Fire Ceremony. In this ceremony old pottery was broken in all homes and all fires in the Aztec realm were put out. Then a new fire was drilled over the breast of a sacrificial victim and runners brought the new fire to the different ‘’calpolli’’ communities where fire was redistributed to each home. The night without fire was associated with the fear that star demons, ‘’ tzitzimime ’’, might descend and devour the earth ending the fifth period of the sun.
To the Aztecs, death was instrumental in the perpetuation of creation, and gods and humans alike had the responsibility of sacrificing themselves in order to allow life to continue. As described in the myth of creation above, humans were understood as responsible for the sun's continued revival, as well as for the paying the earth for its continued fertility. Blood sacrifice in various forms were conducted. Both humans and animals were sacrificed, depending on the god to be placated and the ceremony being conducted, and priests of some gods were sometimes required to provide their own blood through self-mutilation. It is known that some rituals included acts of cannibalism, with the captor and his family consuming part of the flesh of their sacrificed captives, but it is not known how widespread this practice was.
While human sacrifice was practiced throughout Mesoamerica, the Aztecs, if their own accounts are to be believed, brought this practice to an unprecedented level. For example, for the reconsecration of the Great Pyramid of Tenochtitlan in 1487, the Aztecs reported that they sacrificed 80,400 prisoners over the course of four days, reportedly by Ahuitzotl, the Great Speaker himself. This number, however, is not universally accepted.
The scale of Aztec human sacrifice has provoked many scholars to consider what may have been the driving factor behind this aspect of Aztec religion. In the 1970s, Michael Harner and Marvin Harris argued that the motivation behind human sacrifice among the Aztecs was actually the cannibalization of the sacrificial victims. Harner claimed that very high population pressure and an emphasis on maize agriculture, without domesticated herbivores, led to a deficiency of essential amino acids amongst the Aztecs. While there is universal agreement that the Aztecs practiced sacrifice, there is a lack of scholarly consensus as to whether cannibalism was widespread. Harris, author of Cannibals and Kings , has propagated the claim, originally proposed by Harner, that the flesh of the victims was a part of an aristocratic diet as a reward, since the Aztec diet was lacking in proteins. These claims have been refuted by Bernard Ortíz Montellano who, in his studies of Aztec health, diet, and medicine, demonstrates that while the Aztec diet was low in animal proteins, it was rich in vegetable proteins. Ortiz also points to the preponderance of human sacrifice during periods of food abundance following harvests compared to periods of food scarcity, the insignificant quantity of human protein available from sacrifices and the fact that aristocrats already had easy access to animal protein. Today many scholars point to ideological explanations of the practice, noting how the public spectacle of sacrificing warriors from conquered states was a major display of political power, supporting the claim of the ruling classes to divine authority. It also served as an important deterrent against rebellion by subjugated polities against the Aztec state, and such deterrents were crucial in order for the loosely organized empire to cohere.
Art and cultural production
Writing and iconography
The Aztecs did not have a fully developed writing system like the Maya did, but like the Maya and Zapotec they did use a writing system that combined logographic signs with phonetic syllable signs. Logograms would for example be the use of an image of a mountain to signify the word tepetl "mountain", whereas a phonetic syllable sign would be the use of an image of a tooth tlantli to signify the syllable tla in words unrelated to teeth. The combination of these principles allowed the Aztecs to represent the sounds of names of persons and places. Narratives tended to be represented through sequences of images, using different iconographic conventions such as footprints to show paths, temples on fire to show conquest events etc.
Epigrapher Alfonso Lacadena has demonstrated that the different syllable signs used by the Aztecs almost enabled the representation of all the most frequent syllables of the Nahuatl language (with some notable exceptions), but some scholars have argued that such a high degree of phoneticity was only achieved after the conquest when the Aztecs had been introduced to the principles of phonetic writing by the Spanish. Other scholars, notably Gordon Whittaker, have argued that the syllabic and phonetic aspects of Aztec writing were considerably less systematic and more creative than Lacadena's proposal suggests, arguing that Aztec writing never coalesced into a strictly syllabic system such as the Maya writing, but rather used a wide range of different types of phonetic signs.
The image to right demonstrates the use of phonetic signs for writing place names in a colonial Aztec codex. The uppermost place is "Mapachtepec", meaning literally "Raccoon mountain", but the glyph includes the phonetic signs "MA" (hand) and "PACH" (moss) over a mountain "TEPETL" spelling the word " mapach " ("raccoon") phonetically instead of logographically. The other two placenames Mazatlan ("deer place") and Huitztlan ("thorn place") use the phonetic element "TLAN" represented by a tooth ( tlantli ) combined with a deer head to spell "MAZA" ( mazatl = deer) and a thorn ( huitztli ) to spell "HUITZ".
Music, song and poetry
Song and poetry were highly regarded; there were presentations and poetry contests at most of the Aztec festivals. There were also dramatic presentations that included players, musicians and acrobats.
There were several different genres of cuicatl (song): Yaocuicatl was devoted to war and the god(s) of war, Teocuicatl to the gods and creation myths and to adoration of said figures, xochicuicatl to flowers (a symbol of poetry itself and indicative of the highly metaphorical nature of a poetry that often utilized duality to convey multiple layers of meaning). "Prose" was tlahtolli , also with its different categories and divisions.
A key aspect of Aztec poetics was the use of parallelism, using a structure of embedded couplets to express different perspectives on the same element. Some such couplets were diphrasisms, conventional metaphors whereby an abstract concept was expressed metaphorically by using two more concrete concepts. For example, the Nahuatl expression for "poetry" was in xochitl in cuicatl a dual term meaning "the flower, the song", and the term for visual arts was in tlilli in tlapalli – "the black ink, the red paint.
A remarkable amount of this poetry survives, having been collected during the era of the conquest. In some cases poetry is attributed to individual authors, such as Nezahualcoyotl, tlatoani of Texcoco, and Cuacuauhtzin, Lord of Tepechpan, but whether these attributions reflect actual authorship is a matter of opinion. The most important collection of these poems is Romances de los señores de la Nueva España , collected (Tezcoco 1582), probably by Juan Bautista de Pomar. Bautista de Pomar was the great-grandson of Netzahualcoyotl. He spoke Nahuatl, but was raised a Christian and wrote in Latin characters. ( See also: " Is It You? " , a short poem attributed to Netzahualcoyotl, and " Lament on the Fall of Tenochtitlan " , a short poem contained within the " Anales de Tlatelolco " manuscript. )
Visual and plastic art
Aztec visual art was produced on animal skin (mostly deer), on cotton lienzos and on Amate paper made from bark (e.g. from Trema micrantha or Ficus aurea ), it was also produced on ceramics and carved in wood and stone. The surface of the material was often first treated with gesso to make the images stand out more clearly. For ceramics most designs were produced in black ink on the background of an orange slip, this "black on orange" ware being characteristic of the Aztec period.
In the Nahua treatise on art in The Florentine Codex , the venerated painters (the toltecaye ) describe the colors, how they were obtained from nature, how they were produced, and how people painted with them. According to Magaloni Kerpel in The Colors of the New World, the treatise organizes colors according to a system of “complementary polarities.” The colors are divided into the organic (those obtained from plants and insects) and mineral (those obtained from the earth). Furthermore, saturated and vibrant colors contrasted opaque and dark colors. There was also a distinction between primary (red, blue, yellow, black, and white) and secondary colors (green, purple, brown, and ochre). Each color had a specific significance based on their raw material and their natural state. Black ink was largely used to outline colored images. Rather than mixing colors, artists would often layer them in order to make them more intense.
Lastly, most of the colorants and pigments used in the Florentine Codex were of Mesoamerican origin; however, the only European paint pigment found in the codex is minium (red lead). Minium was often so often used in European medieval illuminated manuscripts that those paintings "were called miniatures from miniare in Latin, which means 'to color with red.'" In the Florentine Codex , minium's use was specific: it was used on images that describe or indicate the colonial, Spanish present as a new era of Aztec history. Minimum (the European pigment) represented the present as it was dominated by Spaniards who had one the colonial war, while nocheztli (the Mesoamerican red pigment) represented the primitive, indigenous past of New Spain. Thus, the contrast between the saturated and diluted colors were utilized to indicate two temporalities in Mesoamerican history.
Sculptures were carved in stone and wood, but few wood carvings have survived. Aztec stone sculptures exist in many sizes from small figurines to large monuments, and are characterized by a high quality of work. Ceramics was also used for large sculptures, and decorative vessels.
Most modern-day Mexicans (and people of Mexican descent in other countries) are mestizos, of mixed indigenous and European ancestry. During the 16th century the racial composition of Mexico began to change from one that featured distinct indigenous (Mexicas and members of the many other Mexican indigenous groups) and immigrant (mostly Spanish) populations, to the population composed primarily of mestizos that is found in modern-day Mexico.
The Nahuatl language is today spoken by 1.5 million people, mostly in mountainous areas in the states of central Mexico. Local dialects of Spanish, Mexican Spanish generally, and the Spanish language worldwide have all been influenced, in varying degrees, by Nahuatl. Some Nahuatl words (most notably chocolate , derived from the Nahuatl word xocolatl, and tomato ) have been borrowed through Spanish into other languages around the world.
Mexico City was built on the ruins of Tenochtitlan, making it one of the oldest living cities of the Americas. Many of its districts and natural landmarks retain their original Nahuatl names. Many other cities and towns in Mexico and Central America have also retained their Nahuatl names (whether or not they were originally Mexica or even Nahuatl-speaking towns). A number of town names are hybrids of Nahuatl and Spanish.
Mexican cuisine continues to be based on and flavored by agricultural products contributed by the Mexicas/Aztecs and Mesoamerica, most of which retain some form of their original Nahuatl names. The cuisine has also become a popular part of the cuisine of the United States and other countries around the world, typically altered to suit various national tastes.
The modern Mexican flag bears the emblem of the Mexica migration story.
Before the development of archaeology in Mexico in the 19th century, historians mainly interpreted the records of the Spanish conquerors and the accounts of early European travellers and antiquaries who investigated the enigmatic monuments the Indians left to posterity. It was not until the nineteenth century that the work of men such as John Lloyd Stephens, Eduard Seler and Alfred P. Maudslay, and of institutions such as the Peabody Museum of Harvard University, led to a better appreciation of the evidence available. Subsequently, there emerged indigenous Mexican archaeologists of international caliber. Archaeology allowed the reconsideration and criticism of some of those interpretations and contradictions between the primary sources. Now, the scholarly study of Aztec civilization is most often based on scientific and multidisciplinary methodologies.
There are few extant Aztec codices created before the conquest and these are largely ritual texts. Post-conquest codices, like Codex Mendoza or Codex Ríos, were painted by Aztec tlacuilos (codex creators), but under the control of Spanish authorities. The possibility of Spanish influence poses potential problems for those studying the post-conquest codices. Itzcoatl had the oldest hieroglyphics destroyed for political-religious reasons and Bishop Zumarraga of Mexico (1528–48) had all available texts burned for missionary reasons.
The accounts of the conquistadors are those of men confronted with a new civilization, which they tried to interpret according to their own culture. Cortés was the most educated, and his letters to Charles V are a valuable firsthand account. Unfortunately, one of his letters is lost and replaced by a posterior text and the others were censored prior to their publication. In any case, Cortés was not writing a dispassionate account, but letters justifying his actions and to some extent exaggerating his successes and downplaying his failures.
Bernal Díaz del Castillo accompanied Cortes, and he later wrote a book named: The Discovery and Conquest of Mexico .  In his book, Capitan Bernal Díaz del Castillo provides his account of the Conquest of Mexico, in which he describes the events leading up to the conquest of Mexico, including accounts of the human sacrifices and cannibalism that he witnessed first hand. However, Bernal Díaz wrote several decades after the fact, never learned the native languages, and did not take notes. His account is colorful, but his work is considered by historians to be erratic and exaggerated.
Although Francisco López de Gómara was Cortes' chaplain, friend, and confidant, he never visited the New World so his account is based on hearsay.
Priests and scholars
The accounts of the first priests and scholars, while reflecting their faith and their culture, are important sources. Fathers Diego Durán, Motolinia, and Mendieta wrote with their own religion in mind, Father Duran wrote trying to prove that the Aztec were one of the lost tribes of Israel. Bartolomé de las Casas wrote apologetically about the Indians, accusing the Spanish conquistadors of committing unspeakable atrocities in their subjugation of the Aztecs and other indigenous groups. Some authors tried to make a synthesis of the pre-Hispanic cultures, like "Oviedo y Herrera", Jose de Acosta, and Pedro Mártir de Anghiera.
The most significant source about the Aztec are doubtless the manuscripts of Bernardino de Sahagún, who worked with Christian Aztec youths from Texcoco, Azcapotzalco and Tlatelolco who studying at the Colegio de Santa Cruz de Tlatelolco. With his assistants he interviewed Aztec elders who had knowledge of the prehispanic customs and recorded it in a bilingual 12 volume codex written in parallel Nahuatl and Såpanish columns. The work is now known as the Florentine Codex.
Other important sources are the work of native and mestizo authors, descendants of the upper classes. These authors include Don Fernando Alvarado Tezozómoc, Chimalpahin Cuauhtlehuanitzin, Juan Bautista de Pomar, and Fernando de Alva Cortés Ixtlilxochitl. Ixtlixochitl, for example, wrote a history of Texcoco from a Christian point of view. His account of Netzahualcoyotl, an ancestor of Ixtlilxochitl's, has a strong resemblance to the story of King Solomon and portrays Netzahualcoyotl as a monotheist and a critic of human sacrifice.
- By one series of estimates, the population before the time of the conquest is estimated at 19 million; by 1550, the estimated population was 4 million and by 1581 less than two million
- singular form pilli
- This volume was later translated into Spanish by Ángel María Garibay K., teacher of León-Portilla, and it exists in English translation by John Bierhorst
- Historia Verdadera de la Conquista de la Nueva España, Escrita por el Capitan Bernal Diaz del Castillo, uno de sus conquistadores – Published in the Spanish language by Fernandez, Editores S.A. Mexico City, (Published in the English language by Farrar, Straus and Cudahy in 1956 LCCN)