Final answer:
The Spanish conquistadors conquered the Americas quickly due to superior military technology, strategic alliances with local tribes, and the impact of diseases like smallpox, which decimated indigenous populations.
Step-by-step explanation:
The Spanish conquistadors were able to conquer the Americas rapidly due to military tactics and technological superiority. Specifically, their steel weapons and armor, coupled with cavalry, gave them a decisive advantage over the Native Americans' more primitive arms. Additionally, the Spanish formed alliances with local tribes discontent with Aztec rule, such as the Totonacs, who saw the Spaniards as liberators. A critical, albeit unintended, factor was the introduction of smallpox to the Americas, which devastated indigenous populations and weakened their ability to resist conquest, as seen in the siege of Tenochtitlan in 1521.
The desire for gold and riches was a strong motivator that led the Spaniards to seek new territories. Hernán Cortés and his expedition are prime examples, as they pursued the Aztec Empire for its wealth. The Spaniards inserted themselves in top government positions after conquering, exploiting the existing patterns of tribute and labor systems, such as the Inca mita, for economic gain, particularly in silver mines.