Itzcoatl's greatest military feat came early in his reign: the toppling of the powerful Tepanec empire centered at Azcapotzalco. The Tepanecs were already in a state of turmoil toward the end of Chimalpopoca's rule, with the death of Tezozomoc and the ensuing battle of succession by his sons. Itzcoatl aggressively allied himself with the struggling ruler-in-exile of the Acolhua, Nezahualcoyotl, and together they vanquished the Tepanec forces. But becoming the new lords of the valley was a feat yet to be established, and Itzcoatl spent the remainder of his days (until his death in 1440) conquering dissident towns and consolidating Mexica power in and around the Valley of Mexico. Based on this excerpt, what can you conclude about Mexico's Tepanec empire in the early 1400s?