The Tepanecs or Tepaneca are a Mesoamerican people who arrived in the Valley of Mexico in the late 12th or early 13th centuries. The Tepanec were a sister culture of the Aztecs (or Mexica) as well as the Acolhua and others—these tribes spoke the Nahuatl language and shared the same general pantheon, with local and tribal variations.
Reputedly welcomed to the Valley of Mexico by the semi-legendary Chichimeca ruler Xolotl, the Tepanecs settled on the west shores of Lake Texcoco. Under their tlatoani, Acolnahuacatl, the Tepanec took over Azcapotzalco from the indigenous inhabitants.
In the early 14th century, Tezozomoc brought the Tepanec to their height of power; at that point they controlled nearly all of the Valley of Mexico as well parts of the Toluca and Morelos valleys. Native sources say that Tezozomoc lived to the age of over 100 and was legendary for his generalship and statesmanship.
The death of Tezozomoc in 1426 brought his sons Tayauh and Maxtla to the throne, with Maxtla most likely poisoning Tayauh.