Itzcoatl’s accession marked a leadership change that enabled the Mexica to break Tepanec dominance and pursue a new alliance-based imperial strategy.
Following conflict with Azcapotzalco and the defeat of the Tepanec ruler Maxtla, Tenochtitlan, Texcoco, and Tlacopan formalized a ruling coalition—later known as the Triple Alliance—that became the foundation of the Aztec (Mexica) imperial system.
Nezahualcoyotl’s rule strengthened Texcoco as a major political and cultural partner within the Triple Alliance, helping stabilize governance and administration in the basin of Mexico.
Moctezuma I’s reign is associated with consolidation of the new imperial structure and the growing dominance of Tenochtitlan within the alliance.
Axayacatl’s accession continued the alliance’s expansion and intensified militarized imperial control during the later 15th century.
In 1473, Tenochtitlan defeated its neighboring island-city Tlatelolco, reducing its political autonomy and reinforcing Tenochtitlan’s primacy within the Triple Alliance system.
Ahuitzotl’s rule is widely described as a high-water mark of territorial expansion for the empire built through the Triple Alliance, with campaigns extending far beyond the Valley of Mexico.
A major ceremonial dedication of the Templo Mayor in Tenochtitlan in 1487 symbolized imperial power and religious centrality, drawing participants (and captives) from across the empire.
Moctezuma II became the ninth ruler of the Mexica polity centered on Tenochtitlan, presiding over an empire at great extent but facing intensifying tributary pressures and political tensions.
Hernán Cortés and his forces entered Tenochtitlan on 8 November 1519 and were received by Moctezuma II—an encounter that opened a rapid sequence of political crisis, warfare, and regime collapse.
On 22 May 1520, Spaniards under Pedro de Alvarado killed unarmed Mexica elites during the Toxcatl festival at the Great Temple, accelerating hostilities and undermining any fragile coexistence in the capital.
After Moctezuma II’s death in late June 1520, Cuitlahuac took power and led resistance against the Spanish during a brief reign before dying of smallpox later in 1520.
During the night of 30 June–1 July 1520, Cortés and his forces fled Tenochtitlan under attack, suffering heavy losses—an episode remembered as La Noche Triste (or, in some Mexican usage, Noche Victoriosa).
Cuauhtémoc became tlatoani as the conflict escalated, leading Tenochtitlan’s defense during the final phase of the war against the Spanish-led coalition.
After a prolonged siege (May–August 1521), Tenochtitlan surrendered on 13 August 1521, marking the effective end of the Triple Alliance’s imperial system and the start of Spanish colonial rule in central Mexico.
Aztec Triple Alliance (Tenochtitlan–Texcoco–Tlacopan) (1428–1521)
