The first mention of Danes are from the 6th century in Jordanes' Getica , by Procopius , and by Gregory of Tours . The first mention of Danes within the Danish territory is on the Jelling Rune Stone which states how Harald Bluetooth converted the Danes to Christianity in the 10th century.  Denmark has been continuously inhabited since this period; and, although much cultural and ethnic influence and immigration from all over the world has entered Denmark since then, present day Danes tend to see themselves as ethnic descendants of the early tribal Danes mentioned in the historic sources. Whether this is true or not, the Danish Royal Family can certainly trace their family line back to Gorm the Old (d. 958 AD) in the Viking Age , and perhaps even before that to some of the preceding semi-mythical rulers.
Since the formulation of a Danish national identity in the 19th century, the defining criteria for being Danish has been speaking the Danish language and identifying Denmark as a homeland. Danish national identity was built on a basis of peasant culture and Lutheran theology , theologian N. F. S. Grundtvig and his popular movement played a prominent part in the process.
Today, the main criterion for being considered a Dane is having Danish citizenship . However, other criteria include people with a Danish ancestral or ethnic identity; people living outside Denmark such as emigrants; and descendants of emigrants or members of the Danish ethnic minority in Southern Schleswig , Germany can be considered Danes under a wider definition taking into consideration cultural self-identification.
The first mentions of " Danes " are recorded in the mid 6th century by historians Procopius ( Greek : δάνοι ) and Jordanes ( danī ), who both refer to a tribe related to the Suetidi inhabiting the peninsula of Jutland , the province of Scania and the isles in between. Frankish annalists of the 8th century often refer to Danish kings. The Bobbio Orosius from the early 7th century, distinguishes between South Danes inhabiting Jutland and North Danes inhabiting the isles and the province of Scania.
The first mention of Danes within the Danish territory is on the Jelling Rune Stone which mentions how Harald Bluetooth converted the Danes to Christianity in the 10th century.  Between c. 960 and the early 980s, Harald Bluetooth established a kingdom in the lands of the Danes, stretching from Jutland to Scania. Around the same time, he received a visit from a German missionary who, by surviving an ordeal by fire according to legend, convinced Harold to convert to Christianity .
The following years saw the Danish Viking expansion , which incorporated Norway and Northern England into the Danish kingdom. After the death of Canute the Great in 1035, England broke away from Danish control. Canute's nephew Sweyn Estridson (1020–74) re-established strong royal Danish authority and built a good relationship with the archbishop of Bremen — at that time the Archbishop of all of Scandinavia .
Christianization of Denmark
The Reformation , which originated in the German lands in the early 16th century from the ideas of Martin Luther (1483–1546), had a considerable impact on Denmark. The Danish Reformation started in the mid-1520s. Some Danes wanted access to the Bible in their own language. In 1524, Hans Mikkelsen and Christiern Pedersen translated the New Testament into Danish; it became an instant best-seller. Those who had traveled to Wittenberg in Saxony and come under the influence of the teachings of Luther and his associates included Hans Tausen , a Danish monk in the Order of St John Hospitallers . The Dano-Norwegian Kingdom grew wealthy during the 16th century, largely because of the increased traffic through the Øresund . The Crown of Denmark could tax the traffic, because it controlled both sides of the Sound at the time. After a failed war with Sweden, the Treaty of Roskilde in 1658 removed the areas of the Scandinavian peninsula from Danish control, thus establishing the boundaries between Norway, Denmark, and Sweden that exists to this day. In the centuries after this loss of territory, the populations of the Scanian lands , who had previously been considered Danish, came to be fully integrated as Swedes . Later, in the early 19th century, Denmark suffered a defeat in the Napoleonic Wars ; Denmark lost control over Norway and territories in what is now northern Germany . The political and economic defeat ironically sparked what is known as the Danish Golden Age during which a Danish national identity first came to be fully formed. The Danish liberal and national movements gained momentum in the 1830s, and after the European revolutions of 1848 Denmark became a constitutional monarchy on June 5, 1849. The growing bourgeoisie had demanded a share in government, and in an attempt to avert the sort of bloody revolution occurring elsewhere in Europe, Frederick VII gave in to the demands of the citizens. A new constitution emerged, separating the powers and granting the franchise to all adult males, as well as freedom of the press, religion, and association. The king became head of the executive branch .
Danishness ( danskhed ) is the concept on which contemporary Danish national and ethnic identity is based. It is a set of values formed through the historic trajectory of the formation of the Danish nation. The ideology of Danishness emphasizes the notion of historical connection between the population and the territory of Denmark and the relation between the 1000-year-old Danish monarchy and the modern Danish state, the 19th century national romantic idea of "the people" ( folk ), a view of Danish society as homogeneous and socially egalitarian as well as strong cultural ties to other Scandinavian nations. 
Importantly, since its formulation, Danish identity has not been linked to a particular racial or biological heritage, as many other ethno-national identities have. Grundtvig for example emphasized the Danish language and the emotional relation to and identification with the nation of Denmark as the defining criteria of Danishness. This cultural definition of ethnicity has been suggested to be one of the reasons that Denmark was able to integrate their earliest ethnic minorities of Jewish and Polish origins into the Danish ethnic group. Jewishness for example was not seen as being incompatible with a Danish ethnic identity as long as the most important cultural practices and values were shared. This inclusive ethnicity has in turn been described as the background for the relative lack of virulent anti-semitism in Denmark and the rescue of the Danish Jews , saving 99% of Denmark's Jewish population from the Holocaust.
This ideology of Danishness has been politically important in the formulation of Danish political relations with the EU , which has been met with considerable resistance in the Danish population, and in recent reactions in the Danish public to the increasing influence of immigration.
According to the Danish statistics institute, approximately five million people of Danish origin live in Denmark today. In this context "Danish origin" is defined as being born to parents who are Danish citizens, and the number is arrived at by subtracting from the total population (5,564,249) those who are born abroad to non-citizens who are themselves born abroad (called immigrants), and those who are born in Denmark to parents who are either immigrants or who have foreign citizenship. 
Danish citizenship is granted to anyone who has one parent of Danish citizenship, whether the child is born in or outside of Denmark. Citizens of Greenland and the Faroe islands are considered Danish citizens for all purposes. Those who do not achieve Danish citizenship by birth (or by Adoption) can only receive Danish citizenship through decree of law . Danish citizenship is automatically lost if one applies for foreign citizenship or when a 22-year-old child of Danish citizens has never lived in Denmark and has not formally applied for Danish citizenship.
Danish diaspora consists of emigrants and their descendants, especially those that maintain some of the customs of their Danish culture. A minority of approx. 50,000 Danish-identifying German citizens live in Southern Schleswig in Germany, a former Danish territory, forming around 10% of the local population. In Denmark, the latter group is often referred to as "Danes south of the border" ( De danske syd for grænsen ), the "Danish-minded" ( De Dansksindede ) or simply "South Schleswigers". Due to immigration there are considerable populations with Danish roots outside of Denmark in countries such as United States, Brazil , Canada and Argentina .
Danish Americans ( Dansk-amerikanere ) are Americans of Danish descent. There are approximately 1,500,000 Americans of Danish origin or descent. Most Danish-Americans live in the Western United States or the Midwestern United States. California has the largest population of people of Danish descent in the United States.  Notable Danish communities in the United States are located in Solvang, California and Racine, Wisconsin , but these populations are not considered to be Danes for official purposes by the Danish state, and heritage alone can not be used to claim Danish citizenship, as it can in some European nations (see below).
According to the 2006 Census, there were 200,035 Canadians with Danish background , 17,650 of whom were born in Denmark.   Canada became an important destination for the Danes during the post war period. At one point, a Canadian immigration office was to be set up in Copenhagen . 
The Danish nation in a political context
Det danske folk ( The Danish people ) as a concept, played an important role in 19th century ethnic nationalism and refers to self-identification rather than a legal status. Use of the term is most often restricted to a historical context; the historic German-Danish struggle regarding the status of the Duchy of Schleswig vis-à-vis a Danish nation-state . It describes people of Danish nationality , both in Denmark and elsewhere. Most importantly, ethnic Danes in both Denmark proper and the former Danish Duchy of Schleswig . Excluded from this definition are people from the formerly Norwegian Faroe Islands and Greenland as well as members of the German minority as well as members of other ethnic minorities.
The term should not be confused with the legal concept of nationality , danske statsborgere ( Danish nationals ) i.e. individuals holding Danish citizenship.