What was the reason of the Aztecs end to civilizations?

The end of the Aztec civilization was primarily due to the Spanish conquest led by Hernán Cortés in 1519. The Aztecs were weakened by internal strife, disease outbreaks like smallpox, and the exploitation of their tributary states, which allied with the Spanish against them. The combination of superior Spanish military technology, strategic alliances, and the devastating impact of European diseases ultimately led to the fall of Tenochtitlán in 1521 and the collapse of the Aztec Empire.