The Incas were a group of native South American people who created an empire that was the largest civilization in the New World prior to the arrival of Columbus. The early Incas predominantly inhabited the highlands of the central Peruvian Andes. Cusco (also spelled Cuzco) was their capital city. The Incas were mostly pastoral prior to the fifteenth century. Over the course of the 1400s and early 1500s, the Inca rulers consolidated and expanded their power over other tribes, creating an empire that encompassed an area from present-day Colombia to Chile along most of the length of the Andes. The economy of the Inca empire was based on a unique form of taxed labor in which people were required to contribute part of their labor to the state. In addition, the Incas were masters of civil engineering. For instance, they built a vast expanse of roads and bridges that connected all regions of the empire. They also excelled in their creation of architectural enterprises, building vast administration centers and temples. The citadel complex of Machu Picchu is one of the finest examples of Inca architecture. See also: Civil engineering; South America

The Incas developed excellent methods of terraced farming (terracing) on the steep slopes of the Andes, enhancing the productivity of their agricultural endeavors. The potato was the most important crop for the Incas because of its ability to grow at high altitudes and to withstand heavy frosts. Other important crops included corn (maize) and quinoa. See also: Agricultural science (plant); Agricultural soil and crop practices; Agriculture; Corn; Domestication (anthropology); Potato, Irish; Quinoa; Terracing (agriculture)

Religion played a central role in Inca life. In a connection of religion and the political power of the state, the Incas were ruled by a king, who was the embodiment of a living god. The most important god was that of the Sun (Inti). Astronomy also held a vital role in Inca culture, particularly because of its relation to agriculture. Many of the temple complexes built throughout the Inca empire contained astronomical observatories for the purpose of mapping celestial events over the course of a year. Furthermore, Inca city planning incorporated astronomy in the form of the ceque system of radial lines, which marked the directions to sacred places (from the Temple of the Sun in the valley of Cusco). The ceque system also had calendric connections to the seasons and days of the agricultural year. See also: Archeoastronomy; Archeology; Astronomy; Calendar; Ethnoarcheology; Sun

In the late 1520s and early 1530s, the Spanish conquistador Francisco Pizarro led a series of expeditions that led to the downfall of the Inca civilization. The vast majority of Inca territory fell into Spanish hands by the end of 1532, although some pockets of resistance remained until 1572.