Spanish conquistadors like Hernan Cortes and Francisco Pizarro led expeditions in the early 1500s that conquered the Aztec and Inca empires and established Spain's control over Mexico and Peru. European diseases devastated indigenous populations. The Spanish established three main settlement types: presidios (forts), missions (religious communities), and pueblos (towns). A social hierarchy developed with Spanish-born elites at the top and Native Americans and African slaves facing exploitation, slavery, and oppression at the bottom.