Formation of the Aztec Triple Alliance

Timeline

1. 1427–1428Tenochtitlan · Valley of MexicoTenochtitlan under Itzcoatl joined with Texcoco and Tlacopan to rise against Azcapotzalco's suzerainty, with war spreading throughout the Valley of Mexico.
2. 1428–1430Azcapotzalco · Valley of MexicoThe allied forces captured Azcapotzalco's capital, dismantling its hegemony. The three cities formally concluded an alliance, agreeing on shares of spoils and tribute, and establishing a new order led by Tenochtitlan.
3. 1431–1435Valley of Mexico · Valley of MexicoThe alliance consolidated control over surrounding city-states, establishing tribute systems and military recruitment mechanisms that laid institutional foundations for expansion toward the Gulf Coast and beyond.