What events led to the fall of the Aztec Empire?

The fall of the Aztec Empire was primarily driven by the arrival of Spanish conquistadors, led by Hernán Cortés, in 1519. The Spaniards formed alliances with discontented indigenous groups, such as the Tlaxcalans, who opposed Aztec rule. Key events included the capture of Emperor Moctezuma II and the subsequent siege of Tenochtitlán, which culminated in the city's destruction in 1521. Additionally, the introduction of European diseases, like smallpox, decimated the Aztec population, weakening their ability to resist the conquest.