The answer to this question can be found in Chapter 3 of Guns, Germs, and Steel. There, Diamond describes the “collision at Cajamarca” between the Spanish and the Inca and discusses the factors that allowed the Spanish to come out on top after the collision. One major factor was superior Spanish technology. On p. 80, Diamond sums up the technological factors that helped the Spanish. One of these, writing, is not something that we would typically think of as technology, but it can be seen in that way. The five factors were:
military technology based on guns, steel weapons, and horses; … European maritime technology;… and writing.
Had it not been the European maritime technology, the Spanish would not have been in Peru in the first place. Their ships and the equipment needed to sail and navigate them were something that the Incas lacked. This gave the Europeans a major advantage. The Incas also lacked the military technology the Spanish had. They did not have steel of any sort. Because they did not have steel, they also did not have guns. They did not have horses either, which gave the Spanish a tremendous tactical advantage when fighting the Incas. Finally, the Incas had no real system of writing. This harmed them because they could not write down information and transmit it to other people in different places and/or times. The Spanish had all of these things and the Incas had none. These technological advantages were contributing factors to the European conquest of the Americas.