Aztec (Mexica) Arrive in Valley of Mexico

In the early fourteenth century, a people known as the Mexica, later called the Aztecs, entered the Valley of Mexico and eventually settled on a marshy island in Lake Texcoco. The date of 1300 is approximate. Their settlement there, traditionally dated to 1325, became Tenochtitlan, the capital of what would grow into the largest empire in Postclassic Mesoamerica. The story matters because it shows how a small, politically weak group rose from the margins of a crowded region to dominate it within roughly two centuries.

The valley they entered was far from empty. The great city of Teotihuacan had declined centuries earlier, and the Toltec center of Tula had also faded, leaving a patchwork of competing city-states around the lake system. Groups such as the Tepanecs of Azcapotzalco, the Acolhua of Texcoco, and the people of Culhuacan held the best farmland and claimed prestige through descent from Toltec rulers. Latecomers like the Mexica had little leverage and, according to their own traditions, were often unwelcome.

Mexica accounts describe a long migration from a legendary homeland called Aztlán, guided by their patron god Huitzilopochtli. Historians treat these narratives with caution. They were written down or reshaped after the empire had risen, and they served to give the Mexica a sacred destiny and a respectable pedigree. The location of Aztlán is unknown, and the migration may be partly mythical. What seems clear is that the Mexica were Nahuatl speakers who came from the north or northwest and spent time as clients or mercenaries of more powerful neighbors, including Culhuacan, before being driven off.

According to tradition, they founded Tenochtitlan where an eagle perched on a cactus, a sign promised by their god. The island was unattractive but defensible, and it offered fish, waterfowl, and access to lake trade. Over time the Mexica built causeways, temples, and chinampas, the raised agricultural plots that made the lake margins highly productive. A second island community, Tlatelolco, developed nearby and later became a major marketplace.

For its first century Tenochtitlan was a tributary of the Tepanecs. That changed around 1428, when the Mexica joined Texcoco and Tlacopan in the Triple Alliance, defeated Azcapotzalco, and began expanding by conquest and tribute. By the early sixteenth century the alliance controlled much of central and southern Mexico, and Tenochtitlan may have held well over one hundred thousand people, though estimates vary. Spanish forces and their indigenous allies destroyed the city in 1521. Mexico City now stands on its ruins, and the Mexica heritage endures in the Nahuatl language, place names, foods, and the national flag's eagle emblem.