Azcapotzalco ruled the Mexica as a tributary power before the formation of the Aztec Triple Alliance. The Tepanec city-state was one of the strongest powers in the Basin of Mexico, and Tenochtitlan became part of its political orbit during the early period of Mexica growth.
The Mexica paid tribute to Azcapotzalco and fought in campaigns on behalf of its rulers. This relationship helped Tenochtitlan expand its military experience and agricultural base, even while the island city remained politically subordinate. Tribute could include goods, labor, and military support.
Azcapotzalco’s dominance ended after a succession crisis following the death of its ruler Tezozomoc. Tenochtitlan joined Texcoco and Tlacopan in a war against Maxtla, Azcapotzalco’s successor. Their victory around 1428 produced the Triple Alliance, which later built the empire commonly called the Aztec Empire. Xochimilco, Tlaxcala, and Cholula were important regional polities, but none was the pre-Alliance tributary power described here.