Aztec Triple Alliance - Founding the Aztec Empire

Three Cultural Groups which Combined to Make the Aztec Empire

Aztec Glyphs for the Triple Alliance
Aztec Glyphs for the Triple Alliance: Texcoco (left), Tenochtitlan (middle), and Tlacopan (right). Goldenbrook

The Triple Alliance (1428-1519) was a military and political accord among three groups living in the Basin of Mexico (what is essentially Mexico City today): Aztec of Tenochtitlán, and other two Nahua city-states of the Valley of Mexico: Texcoco and Tlacopán (Tacuba). It was that accord the formed the basis of the Aztec Empire, who together ruled Central Mexico and eventually most of Mesoamerica at the very end of the Postclassic period.

We know quite a bit about the Aztec Triple Alliance, because histories were compiled at the time of the Spanish conquest in 1519. Many of the native historical traditions collected by the Spanish or preserved in the towns contain detailed information about the dynastic leaders of the Triple Alliance, and economic, demographic and social information comes from the archaeological record.

Rise of the Triple Alliance

The late Postclassic or Aztec Period (AD 1350-1520) in the Basin of Mexico was a time of rapid centralization of political authority. Up until that time, the Basin had been divided among several small city-states (called altepetl in the Nahuatl language) which were each ruled by a petty king (tlatoani). Each atlepetl included an urban administrative center and a surrounding territory of dependent villages and hamlets. The city-states vied with one another for local prominence: and some began to form alliances or confederations for mutual defense

By the late 14th century, two dominant confederations emerged: the Tepaneca on the western side of the Basin, and the Acolhua on the eastern side. In 1418, the Tepaneca under the king Azcapotzalco came to control most of the Basin. Ten years later, the combined forces of three of the city states under Azcapotzalco's control, Tenochtitlán, Texcoco and Tlacopán, defeated the Tepanecs.

Expansion and the Aztec Empire

In 1431, the three rulers agreed formally to a three-fold division of the basin: Tlacopán west of the lake, Texcoco in the east and Tenochtitlán in the south, each politically autonomous, each ruler king and head of is domain.

They were a formidable military and economic force as well agreeing not to engage in war against one another and to cooperate in wars of conquest against other towns. The booty generated from these conquests was then unevenly divided as tribute among the three: two-fifths to Tenochtitlán, two-fifths to Texcoco and only one-fifth to Tlacopán. This tribute system guaranteed the three cities a flow of products coming from different environmental and cultural regions, increasing their power and prestige.

Domination and Disintegration

Although the tribute system remained in place, however, the king of Tenochtitlán soon emerged as the supreme commander of the alliance, and made the final decision on military actions. Eventually, Tenochtitlán began to erode the independence of first Tlacopán, then Texcoco. Of the two, Texcoco remained fairly powerful, appointing its own colonial city-states and able to fend off Tenochtitlán's attempt to intervene in Texcocan dynastic succession right up until the Spanish conquest.

Most scholars believe that Tenochtitlán was dominant through most of the period, but the effective union of the alliance remained intact through political, social and econoimcms means. Each controlled their own territorial domain of dependent city-states and their own military forces. They shared the expansionist goals of the empire, and their highest-status individuals maintained individual soveriegnty by inter-marriages, feasting, markets and tribute sharing across alliance borders.

But hostilities among the Triple Alliance persisted, and it was with the help of Texcoco's forces that Hernan Cortes was able to overthrow Tenochtitlán in 1591.


This glossary entry is a part of the guide to Aztecs, and the Dictionary of Archaeology.

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Updated by K. Kris Hirst