Key Facts
- Duration
- 1428–1521 (Triple Alliance)
- Peak area
- ~300,000 km²
- Peak population
- ~6 million
- Alliance members
- Mexico-Tenochtitlan, Tetzcoco, Tlacopan
- Defeated by
- Hernán Cortés and native allies, 1521
Imperial Zenith Metrics
Territorial Scale Comparison
Peak area vs modern sovereign states
Historical Trajectory
Phase I: Rise
The Triple Alliance emerged in 1428 from the victorious factions of a civil war against the city of Azcapotzalco and its former tributary provinces. The three Nahua city-states — Tenochtitlan, Tetzcoco, and Tlacopan — united to wage wars of conquest, rapidly expanding control across the Valley of Mexico and beyond. Tenochtitlan steadily became the dominant military power within the alliance.
Phase II: Zenith
At its height the alliance controlled most of central Mexico, stretching to distant territories including the Xoconochco exclave near the present-day Guatemalan border. Aztec rule was largely hegemonic: conquered rulers retained power in exchange for semi-annual tribute and military service. This arrangement sustained an integrated economic network across diverse lands, while the capital Tenochtitlan grew into a major urban and religious center.
Phase III: Decline
By 1519, Spanish conquistador Hernán Cortés arrived and exploited widespread resentment among peoples subjugated by Aztec tribute demands. Cortés built a coalition of native allies and, after prolonged siege warfare, captured Tenochtitlan in 1521. The fall of the capital ended the Triple Alliance, incorporating its former territories into the Spanish colonial Viceroyalty of New Spain and dismantling the imperial political and religious order.
Notable Imperial Reigns
Selected rulers mapping the empire’s trajectory