A military alliance formed in 1428 AD, in the Late Post-Classic Period, between Tenochtitlán, Texcoco, and Tacuba and which became the dominant force in the Lake Texcoco region of the Basin of Mexico. They joined together to overthrow the Tepenacs in the city-state of Azcapotzalco. The Aztecs eventually dominated the alliance, although Texcoco, under philosopher-king Nezahuacoyotl, became a renowned center of culture and learning.