[2] Upon Tezozomoc's death in the year Twelve Rabbit (1426), Tayatzin became a king, but Maxtla seized power at Azcapotzalco, leaving the rulership of Coyoacán to his son Tecollotzin.

[3] Emperor Chimalpopoca of Tenochtitlan allied with Tayatzin, and the two conspired to retake the throne and kill Maxtla.

Friendly relations between Tenochtitlan and Azcapotzalco were thus replaced by insults and violent intrigue, apparently involving tit-for-tat assassination attempts.

[4] When Maxtla laid siege to Tenochtitlan in 1428, Chimalpopoca's successor and uncle, Itzcoatl, repelled his forces with the aid of an alliance of city states, including Texcoco under Nezahualcoyotl and many former Tepanec allies, notably Tlacopan.

[5] The victorious powers formalized their relationship in the Triple Alliance of Tenochtitlan, Texcoco and Tlacopan, which would become the basis of the Aztec Empire.