North America 1427: Tepanec War

The Mexica—the last of a number of Nahua people who migrated from among the Chichimeca of northern Mexico to settle in the Valley of Mexico—founded Tenochtitlan on an island in Lake Texcoco in 1325. Rising to prominence as fierce warriors, they threw off the domination of the Tepanecs in 1427–28 and established the Triple Alliance of Tenochtitlan, Texcoco, and Tlacopan soon after. This alliance would form the basis of what would become known as the Aztec Empire (“Aztec” being a mystical name for the Nahua).

Main Events

1427–1428 Tepanec War

In 1426 the Tepanec ruler Tezozomoc died, leading to an uneasy succession as one son, Maxtla, usurped his elder half-brother Tayatzin. The Mexica city of Tenochtitlan rebelled against Maxtla’s authority, allying with Texcoco and other city states to sack the Tepanec capital of Azcapotzalco. After sacrificing Maxtla, the victorious cities formed the Triple Alliance of Tenochtitlan, Texcoco, and Tlacopan, laying the foundation of the Aztec wikipedia

1427–1440 Reign of Itzcoatl

Following the defeat of the Tepanecs and the formation of the Aztec Triple Alliance, Tenochtitlan emerged as the most powerful altapetl (city-state) in the Valley of Mexico. The king of Tenochtitlan, Itzcoatl, became effective leader of the Triple Alliance and quickly used his newfound power to consolidate Aztec control over the Valley of Mexico. During his reign (1427–1441), Itzcoatl conquered the remaining cities around Lake Texcoco in the middle of the valley before moving south to capture Cuauhnahuac (Cuernavaca).in wikipedia