What led to the all of the Aztec empire?

The fall of the Aztec Empire was primarily due to a combination of internal strife, external invasion, and disease. Spanish conquistador Hernán Cortés and his forces, aided by indigenous allies who opposed Aztec rule, launched a successful campaign against the empire in 1519. Additionally, the spread of diseases like smallpox, introduced by Europeans, devastated the indigenous population and weakened their ability to resist conquest. This combination of military defeat and demographic collapse ultimately led to the empire's downfall.