Aztec Empire Timeline

Tenochtitlan Founded

Following an omen their god had promised — an eagle on a cactus devouring a snake — the Mexica people found their capital city on an island in Lake Texcoco.

Why it mattered: Tenochtitlan grew into one of the largest cities in the world, home to about 200,000 people, larger than almost any city in Europe at the time.

Triple Alliance Formed

The Mexica join with the nearby cities of Texcoco and Tlacopan to form the Triple Alliance, launching rapid conquests across central Mexico.

Why it mattered: The Triple Alliance became the Aztec Empire — within decades it controlled most of central Mexico, with millions paying tribute to Tenochtitlan.

The Empire Expands

Under rulers like Moctezuma I and Ahuitzotl, Aztec warriors push the empire to the Gulf Coast, into Oaxaca, and down the Pacific coast to Soconusco, demanding tribute from hundreds of towns.

Why it mattered: The empire's power rested on tribute: conquered peoples paid in goods and labor, and captives taken in war were sacrificed, funding Tenochtitlan's great temples and markets.

Dedication of the Great Temple

The Templo Mayor — the great pyramid at the heart of Tenochtitlan — is expanded and rededicated with elaborate ceremonies.

Why it mattered: The Templo Mayor was the religious center of the Aztec world, honoring Huitzilopochtli (god of war and the sun) and Tlaloc (god of rain) — the two forces the Aztecs believed sustained the universe.

Moctezuma II Becomes Emperor

Moctezuma II becomes the ninth tlatoani (ruler) of Tenochtitlan, presiding over the empire at its height.

Why it mattered: Moctezuma expanded the empire's reach and centralized power in Tenochtitlan — but his reign would end with the Spanish arrival.

Cortes Arrives

Spanish conquistador Hernan Cortes lands on the Gulf Coast with about 500 soldiers, plus horses and cannons, which the Aztecs had never seen before.

Why it mattered: Cortes found many peoples conquered by the Aztecs who were eager to join him against their rulers. A year later, Spanish ships also brought smallpox, a disease new to the Americas.

Cortes Enters Tenochtitlan

Moctezuma II allows Cortes and his soldiers to enter the capital; Cortes eventually takes Moctezuma prisoner inside his own palace.

Why it mattered: The Spanish were able to enter because of indigenous allies, strategic boldness, and because many Aztec-subject peoples saw the Spanish as a chance for liberation from Aztec tribute demands.

La Noche Triste

Moctezuma dies while a prisoner of the Spanish. Days later, Aztec warriors drive the Spanish out of Tenochtitlan in a night of fierce fighting, and Cortes suffers heavy losses.

Why it mattered: The defeat showed the power of Aztec warriors. But a few months later smallpox swept through the city, killing many people, including the new ruler Cuitlahuac.

Siege of Tenochtitlan

Cortes returns with tens of thousands of indigenous allies and lays siege to Tenochtitlan for nearly three months; the city falls on August 13 and the last emperor Cuauhtemoc is captured.

Why it mattered: The fall of one of the world's greatest cities marked the end of the Aztec Empire — and the deaths of millions from European diseases transformed the Americas forever.

Colonial New Spain

The Spanish build Mexico City on the ruins of Tenochtitlan and establish New Spain; Aztec culture, religion, and people are suppressed but never fully erased.

Why it mattered: Aztec language, art, food, and traditions survived the conquest — millions of people of Aztec descent still live in Mexico today, and Nahuatl words like tomato, chocolate, and avocado are used worldwide.