Answer:
better technology and European diseases such as Smallpox
Step-by-step explanation:
Francisco Pizarro defeated the Inca empire in South America and Hernan Cortes defeated the Aztec empire (now Mexico). The two major reason that helped these conquistadors to defeat empires are better technology and disease such as Smallpox.
European have high technology weapons such as portable guns, use of gunpowder while Inca and the Aztec empire had less sophisticated weapons like steel-edged crossbows, swords, and pikes.
European diseases such as smallpox affected indigenous peoples of the Americas and caused large decline in the population of native American that was a big advantage.
Hence, the two major reason were better technology and European diseases such as Smallpox .