Smallpox, which was introduced by Christopher Columbus had a devastating affect on the Aztecs by the time Cortes had arrived. In fact, it made it much easier for him to defeat them. After the Aztecs, the disease turned southward like a tidal wave decimating Central American cultures. Then in 1527, it turned its sights on the Incas and killed the Emperor Huayna Capac and his heir. This touched of a war of succession between Huayna Capacs sons Huascar and Atahualpa. It was about this time Francisco Pizzaro entered Peru with a license from the Spanish Crown to pillage the country.