The Aztec Empire (1325-1521)

The Mexica people, the last Nahua migrants to arrive in central Mexico, founded their capital city of Tenochtitlan on a small island in Lake Texcoco. According to Mexica tradition, they chose the site after witnessing an eagle perched on a cactus devouring a serpent — an omen prophesied by their god Huitzilopochtli. This symbol appears on the modern Mexican flag.

Acamapichtli, of noble Culhua lineage, was enthroned as the first tlatoani (ruler) of Tenochtitlan, establishing the Mexica royal dynasty. During this period, Tenochtitlan served as a tributary of the powerful Tepanec city-state of Azcapotzalco, with the Mexica providing military service in exchange for protection.

Following the death of Tepanec king Tezozomoc in 1426, a succession crisis led to war. Tenochtitlan under Itzcoatl, allied with the exiled king of Texcoco, Nezahualcoyotl, and the dissident Tepanec city of Tlacopan, defeated Azcapotzalco. The three victors formed the Triple Alliance in 1430, marking the formal beginning of the Aztec Empire. Tepanec lands were divided among the allies.

Moctezuma I was crowned huetlatoani (emperor) and, with his adviser Tlacaelel, enacted sweeping political and religious reforms. He expanded the empire east toward the Gulf of Mexico and south into Oaxaca, established a new tribute system with imperial tax collectors, created non-hereditary nobility titles for commoners, and codified laws separating nobles and commoners. He also ordered the rewriting of Aztec history to elevate the Mexica role.

A severe four-year drought struck the Basin of Mexico, causing widespread crop failure and famine. Thousands died of starvation. In response, Tlacaelel reportedly instituted the Flower Wars (xochiyaoyotl) — ritualized, pre-arranged battles with neighboring city-states like Tlaxcala — to capture prisoners for human sacrifice, believed to appease the gods and restore balance.

Axayacatl, the Mexica emperor, launched a major invasion of the Purepecha (Tarascan) Empire with a 32,000-strong army — the first major expansion attempt westward. The Purepecha met them near the border with 50,000 soldiers and inflicted a devastating defeat, killing or capturing over 90% of the Aztec force. Axayacatl himself was wounded and retreated, and the Aztecs never again seriously threatened the Purepecha Empire.

Moctezuma II (also known as Moctezuma Xocoyotzin) was crowned as the ninth tlatoani of Tenochtitlan. Under his rule, the Aztec Empire reached its maximum territorial extent, stretching from the Gulf of Mexico to the Pacific Ocean. Moctezuma centralised power, replaced many provincial governors with Mexica loyalists, and maintained the empire's tributary system, demanding ever more tribute from conquered regions.

Hernan Cortes and his Spanish expedition, accompanied by thousands of indigenous allies (notably the Tlaxcalans, traditional enemies of the Aztecs), arrived in Tenochtitlan. Moctezuma II received them with elaborate hospitality, believing Cortes might be the returning god Quetzalcoatl according to some accounts, though this interpretation is contested by modern scholars. Cortes soon took Moctezuma hostage in his own palace.

After a massacre at the Templo Mayor by Spanish forces during a religious festival sparked a massive Mexica uprising, Cortes and his forces attempted to flee Tenochtitlan by night. The retreat turned into a slaughter as Mexica warriors attacked from boats and causeways. Hundreds of Spaniards and thousands of Tlaxcalan allies were killed or captured and sacrificed. Cortes reportedly wept beneath a tree (the "Tree of the Sad Night") as he escaped the city.

After a 93-day siege, Spanish forces under Cortes and tens of thousands of indigenous allies stormed Tenochtitlan. The last emperor, Cuauhtemoc, was captured while attempting to flee by canoe. The city was largely destroyed, and the Aztec Empire ceased to exist. The Spanish established Mexico City on Tenochtitlan's ruins, and the region became the core of the Viceroyalty of New Spain.