The legendary origin of the Aztec people has them migrating from a homeland called Aztlan to what would become modern-day Mexico. While it is not clear where Aztlan was, a number of scholars believe that the Mexica—as the Aztec referred to themselves—migrated south to central Mexico in the 13th century.

The Mexica founding of Tenochtitlan was under direction from their patron god Huitzilopochtli, according to legend. The legend recounts that Huitzilopochtli told them to found their settlement in the place where a giant eagle eating a snake was perched on a cactus. This settlement, in the region of Mesoamerica called Anáhuac located on a group of five connected lakes, became Tenochtitlan. Archaeologists date the founding of Tenochtitlan to 1325 C.E.

At first, the Mexica in Tenochtitlan were one of a number of small city-states in the region. They were subject to the Tepanec, whose capital was Azcapotzalco, and had to pay tribute to them. In 1428, the Mexica allied with two other cities—Texcoco and Tlacopan. They formed the Aztec Triple Alliance and were able to win the battle for regional control, collecting tribute from conquered states.

Key to the rise of Tenochtitlan was the agricultural system that made it possible to feed the population. Chinampas, small, artificial islands created above the waterline, were one feature of the system. Recordkeeping was important to tracking tributes. Two pictographic texts that survived Spanish destruction—the Matricula de tributos and Codex Mendoza—record the tributes paid to the Aztecs. The codices also recorded religious practices.

A 260-day ritual calendar was used by Aztec priests for divination, alongside a 365-day solar calendar. At their central temple in Tenochtitlan, Templo Mayor, the Aztecs practiced both bloodletting (offering one’s own blood) and human sacrifice as part of their religious practices. The Spanish reaction to Aztec religious practices is believed to be partially responsible for the violence of the Spanish conquest.

The Spanish, led by conquistador Hernando Cortés, arrived in what is now Mexico in 1519. They were looking for gold, and the gifts from the Mexica ruler, Motecuhzoma, proved that gold was present. Upon arriving in Tenochtitlan, Cortés took Motecuhzoma prisoner and attempted to rule on his behalf, but this did not go well, and Cortés fled the city in June of 1520.

This was not the end of the interactions, however. The Spanish conquistadors laid siege to the Aztec capital from the middle of May of 1521 until they surrendered on August 13, 1521. They were aided by Texcoco, a former Triple Alliance member.A great deal of Tenochtitlan was destroyed in the fighting, or was looted, burned, or destroyed after the surrender. Cortés began to build what is now known as Mexico City, the capital of a Spanish colony of which he was named governor, atop the ruins.