“So many people were being carried off by disease—they had no immunity,” he says.
Smallpox and other diseases, introduced to South America by the Spaniards, ravaged the Inca populations, Harl says, causing an internal weakening that helped the Francisco Pizarro-led conquest of 1532. “So many people were being carried off by disease—they had no immunity,” he says. “So rather than the state itself weakening in any significant way, it was disease introduced by the outside that helped prepare for the Inca toppling of civilization in Peru.”