The Inca Empire spanned much of western South America from Colombia to central Chile. It was divided into four regions each governed by appointees who oversaw productive valleys, cities, and mines. Inca society was strictly stratified with the Sapa Inca as ruler and nobility, common people, and servants comprising other classes. The Incas developed advanced infrastructure including roads, architecture, agriculture, and education systems, but the empire disintegrated after the death of Huayna Capac due to a war between his two sons over succession to the throne.