The formation of the Triple Alliance in 1428 was the founding event of the Mexica empire. Through a coalition of three Nahua city-states, the Mexica, the Acolhua of Texcoco, and the Tepanecs of Tlacopan, the peoples of the Valley of Mexico overthrew the Tepanec Empire of Azcapotzalco and began a century of imperial expansion that would make the Mexica the dominant power of central Mexico. The Triple Alliance was a unique political entity, neither a unified state nor a loose confederation, but a coalition of three sovereign cities that agreed to share the costs and benefits of imperial expansion. The alliance would last for nearly a century, and it would be the political framework within which the Mexica developed their imperial institutions and their imperial religion.
The Fall of the Tepanec Empire
The Triple Alliance was formed in response to the growing power of the Tepanec Empire of Azcapotzalco, which by the early fifteenth century had come to dominate much of the Valley of Mexico. The Tepanecs, led by the king Tezozomoc, had built a powerful state through a combination of conquest, marriage alliances, and diplomatic skill. They had reduced several of the smaller city-states of the valley to tributary status, and they had forced the Mexica of Tenochtitlan to accept subordinate status and to pay regular tribute.
Tezozomoc died in 1426, and his death was followed by a succession crisis that weakened the Tepanec state. Maxtla, the new king of Azcapotzalco, was an aggressive ruler who was determined to consolidate Tepanec power and to suppress potential rivals. He was particularly hostile to the Mexica, whose growing power and prosperity threatened Tepanec interests. Maxtla’s aggressive policies provoked a coalition of his enemies, including the Mexica, the Acolhua of Texcoco, and the Otomi of nearby towns.
The leader of the Mexica at this time was Itzcoatl, the fourth Tlatoani of Tenochtitlan. His name, “obsidian serpent,” is said to refer to the sharpness of his political mind. A skilled politician and a brilliant military leader, he had been chosen as Tlatoani in 1427. He was determined to overthrow the Tepanec yoke and to establish Mexica independence. The leader of the Acolhua was Nezahualcoyotl, the king of Texcoco, a brilliant ruler who had been in exile since the Tepanec conquest of his city in 1418 and who had returned to his throne with Mexica support.
The Formation of the Alliance
The military campaign against Azcapotzalco began in 1428, when the coalition of Tenochtitlan, Texcoco, and Tlacopan launched a coordinated attack on the Tepanec heartland. The war was hard-fought, and it lasted for about two years. The decisive battle took place in 1430, when the coalition forces defeated the Tepanec army and captured Azcapotzalco. Maxtla was killed in the fighting, and the Tepanec state was destroyed.
The victory over Azcapotzalco was followed by the division of the Tepanec territories among the three allies. Tenochtitlan received the lion’s share, including the Tepanec heartland around the western Valley of Mexico. Texcoco received the eastern part of the valley and the Acolhua heartland. Tlacopan received a smaller share, including parts of the western Valley of Mexico and access to the Tarascan frontier.
The new political arrangement was formalized in 1428, when the three allies agreed to share the costs and benefits of future imperial expansion. The terms of the alliance, recorded in the Codex Mendoza and other sources, specified that Tenochtitlan would receive two-fifths of the tribute from future conquests, Texcoco would receive two-fifths, and Tlacopan would receive one-fifth. The alliance was to be perpetual, and the three cities were to consult each other on matters of war and peace.
The Imperial Expansion
The years following the defeat of Azcapotzalco saw a rapid expansion of the new empire. The first targets were the remaining Tepanec territories and the smaller city-states of the Valley of Mexico. The Mexica and their allies conquered these territories in a series of campaigns, and they incorporated them into the empire as tributary provinces. The new provinces were required to pay tribute in the form of goods and labor, and they were placed under the supervision of Mexica officials.
The next major target was the rich agricultural region of the southern Valley of Mexico, particularly the city-states of Xochimilco and Chalco. These cities had been among the most prosperous in the valley, and they had been reluctant to accept Mexica dominance. The Mexica and their allies conquered them in a series of campaigns in the 1430s and 1440s, and they incorporated them into the empire. The conquest of the southern Valley of Mexico gave the Mexica control of the most productive agricultural region in central Mexico, and it provided the food surplus that would support the further expansion of the empire.
The reign of Moctezuma I, who ruled from 1440 to 1469, saw the empire expand beyond the Valley of Mexico. The Mexica and their allies conquered the Huastec region to the north, the Mixtec region to the south, and the Gulf Coast lowlands to the east. The conquest of these regions brought the empire into contact with a wide range of peoples and cultures, and it required the development of new techniques of imperial administration. The Mexica dealt with the conquered peoples through a combination of force, diplomacy, and the imposition of tribute obligations. The conquered peoples were generally allowed to retain their local rulers and their local customs, and they were required only to pay tribute and to provide military service.
The Internal Politics of the Alliance
The Triple Alliance was a complex political entity, and the relationships among the three members were often tense. The Mexica of Tenochtitlan, as the senior partner, were the most aggressive in expanding the empire and in extracting tribute from the subject provinces. Texcoco, with its own imperial ambitions and its own tradition of cultural and intellectual achievement, often chafed under Mexica dominance. Tlacopan, the smallest and most subordinate of the three, depended on the other two for its survival.
The internal politics of the alliance were also shaped by the rivalry among the three royal families. The Mexica royal family, the descendants of Acamapichtli, dominated the imperial court and the imperial administration. The Acolhua royal family, the descendants of Nezahualcoyotl, dominated the intellectual and cultural life of the empire. The Tepanec royal family of Tlacopan was a junior partner, and its influence was limited. The rivalry among the three families was a constant feature of imperial politics, and it sometimes led to open conflict, particularly when the succession to one of the three thrones was disputed.
The Limits of Imperial Expansion
The Mexica empire reached its greatest extent under the reign of Ahuitzotl, who ruled from 1486 to 1502. Ahuitzotl was a relentless warrior who carried out the dedication of the reconstructed Templo Mayor in 1487, an event recorded in many sources and described in detail in the Florentine Codex. His reign was marred by one of the great natural disasters of Mexica history: a great flood in 1499, possibly a partial failure of the Nezahualcoyotl dike, that devastated Tenochtitlan and forced a major reconstruction of the city’s infrastructure.
The Mexica empire was not able to conquer all of Mesoamerica. The Tarascan Empire of Michoacán, to the west, was a powerful state that successfully resisted Mexica conquest. The Tlaxcalans, to the east, were a fiercely independent people who maintained their independence throughout the imperial period, and they were the principal allies of the Spanish in the conquest of the Mexica state. The limits of Mexica expansion were an important factor in the eventual Spanish victory, and they shaped the political landscape of central Mexico on the eve of the conquest.
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See also:
- Who were the three rulers who formed the Triple Alliance? — Itzcoatl, Nezahualcoyotl, and Totoquihuaztli
- How did the Triple Alliance defeat the Tepanec Empire? — the campaign of 1428
- What was the role of Tlacopan in the Triple Alliance? — the junior partner
- Origins and Migration of the Aztecs — the Mexica before the alliance
- Provincial Administration and Tributary States — the government of the conquered provinces
- The Tlatoani and the Imperial Office — the rulers of Tenochtitlan
- History of the Aztec Civilization — the broader historical context