* Superior weaponry: The Spanish had guns, cannons, and steel swords, while the Aztecs and Incas had only obsidian-tipped weapons.
* Disease: The Spanish brought diseases such as smallpox and measles to the Americas, which devastated the native populations.
* Horses: The Spanish had horses, which gave them a significant advantage in mobility and transportation.
* Alliances: The Spanish were able to form alliances with native groups who were resentful of Aztec and Inca rule.
* Military strategy: The Spanish were experienced military commanders, while the Aztecs and Incas were often caught off guard by the Spanish tactics.
The Spanish advantages were too much for the Aztecs and Incas to overcome, and ultimately led to their defeat.