At that time, Tenochtitlan was a tributary of the Tepanec city of Azcapotzalco, which was ruled by his grandfather Tezozomoc.

This alliance, and the Mexicas' position within it, was strengthened by Tenochtitlan's loyalty during Tezozomoc's 1418 war with Ixtlilxochitl I of Texcoco.

Gerónimo de Mendieta, in his Historia eclesiástica indiana, notes the discrepancy and concludes that Huitzilihuitl, Chimalpopoca and Itzcoatl (Chimalpopoca's successor) must have been brothers, based on his understanding of the Aztec system of succession.

Three versions of the family tree of the first Aztec rulers: Chimalpopoca was a grandson of Acamapichtli and Tezozomoc and half-brother of Moctezuma I.

However, Itzcoatl quickly allied himself with Nezahualcoyotl of Texcoco and Totoquihuatzin of Tlacopan, and they collectively took down Maxtla, who had remained the Tepanec king.