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c. 1325 CEReputable source · 2 sourcesDebated

An Eagle on a Cactus Marks the Site of Tenochtitlan

After generations of wandering and rejection, the Mexica find the sign their god promised on a marshy island in Lake Texcoco

On the timeline · around c. 1325 CE · Subjects of the TepanecMigration and the Founding of TenochtitlanSubjects of the TepanecAn Eagle on a Cactus Marks the Site of Tenochtitlan1275130013251350

Quick facts

Traditional founding date
1325 CE (some sources give 1345)
Location
Island in Lake Texcoco, Valley of Mexico
Founding sign
Eagle on a cactus devouring a snake
City name origin
Tetl (rock) + nochtli (cactus) + tlan (place)

What happened

The Mexica's migration story reaches its climax with the killing of a rebel named Copil, son of Huitzilopochtli's sister Malinalxochitl, who had led an uprising against the wandering clan. World History Encyclopedia recounts that Huitzilopochtli ordered Copil's heart thrown as far as possible into Lake Texcoco, and that wherever it landed would mark where the Mexica should build their home. An eagle sitting on a prickly-pear cactus and devouring a snake appeared at that spot on a small, unpromising island in the lake, exactly as the god had promised generations earlier. The traditional date most often cited for the founding is 1325, though World History Encyclopedia's own reference material and other chroniclers give 1345, a discrepancy that reflects genuine disagreement among the surviving pictorial annals rather than a settled fact. Luis Barjau, former head of ethnohistory at Mexico's National Institute of Anthropology and History, has argued for March 13, 1325 specifically, a date first popularized for the city's 600th anniversary celebration in 1925.

Why it matters

The eagle-and-cactus sign became the founding symbol of Mexico itself, still on the national flag today. For the Mexica at the time it meant a permanent home after a long period without one, on ground so marginal that no rival city-state had bothered to claim it, which forced them to build outward into the lake rather than simply occupy existing land.

How we know

The story comes from Nahuatl pictorial and alphabetic sources compiled after the conquest, including the Codex Mendoza and the Aubin Codex, which disagree on the exact year. Modern historians treat 1325 as the traditional consensus date while acknowledging the sources themselves are not unanimous.

Sources

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Part of a timelineThe Aztec Empire25 events · From a wandering clan on a swampy island to the dominant power of Mesoamerica, and its end in a 93-day siegeView all →