1. Superior military technology: The Spanish were equipped with advanced military technology, including firearms, cannons, and steel weapons, which gave them a significant advantage over the Aztecs and Incas.
2. Political divisions: Both the Aztecs and Incas were facing internal political divisions and conflicts, which weakened their ability to resist the Spanish invasion.
3. Disease: The Spanish brought with them diseases, such as smallpox and measles, to which the indigenous populations had no immunity. These diseases decimated the native populations and further weakened their resistance to the Spanish.
4. Alliances: The Spanish were able to form alliances with some native groups who were disaffected with the Aztec or Inca rule, which further strengthened their position.
5. Leadership and strategy: The Spanish were led by able and experienced military leaders, such as Hernán Cortés and Francisco Pizarro, who were able to develop effective strategies for defeating the Aztecs and Incas.
6. Cultural differences: The Spanish were able to take advantage of the cultural differences between the Aztecs and Incas to undermine their resistance. For example, the Spanish used their knowledge of Christian theology to convince some native leaders that the Spanish god was more powerful than their own gods.
It is important to note that the conquest of the Aztec and Inca empires was a complex and multifaceted process, and the factors listed above are not exhaustive. The conquest had a profound impact on the indigenous populations of the Americas and shaped the course of history in the region.