Reasons for spanish victories Aztecs and Incas?

There were several reasons that the spanish were able to defeat the Aztecs, and these applied to the Incas as well. The Spanish had much more advanced technology than the Aztecs, such as gunpowder, horses, cannons, and steel weapons (which were stronger than the Aztec obsidian blades). The Spanish also had the advantage of surprise, as they were welcomed into the Aztec empire as honored guests but abruptly betrayed and slaughtered many Aztec citizens before they were driven from the city. Third, European diseases such as smallpox took their toll on the Aztec people. Finally, the Aztecs did not continue and finish defeating the Spanish after La Noche Triste, the only major Aztec victory during the conquest. The Spanish survivors were thus able to regroup and return with more soldiers.