The Incan Empire was conquered by the Spanish, led by Francisco Pizarro and his brothers, between 1532 and 1572. Though the Incas resisted, they were weakened by smallpox and civil war, which helped the Spanish defeat them and subsequently destroy much of their culture.
The biggest contributor to the Incan defeat was disease. Between 60 and 94 percent of the Incan population was decimated by smallpox before the Spanish first arrived. This left the empire weakened. In addition, a bloody civil war between Atahualpa and Huáscar, the sons of the deceased Incan ruler Huayna Capac, divided the Incans and allowed the Spanish to exploit the social rifts that formed, which aided in their eventual conquest.