How were the spanish able to defeat native american empires

The Spanish had superior weapons--their rifles and iron swords against the arrows and stone-bladed swords of the Native Americans. And something else which is too often ignored is the fact that the Spanish made use of Tribal or I should say National rivalries existing between the Aztec and Inca, who were in power in pre-colombian times, and those groups they had conquered or threatened. In the case of the Aztec there were the Toltecs and with the Incas, the Guarani. And of course there were these European diseases like small pox or malaria which the Amerindians had no immunity against.