The largest pre-Hispanic empire of South America, at its height the Incas controlled all of the western part of the continent between Ecuador and Chile in the 15th-16th centuries AD.
The Incas were a distinct people with a distinct language living in a highland centre, Cuzco. They began to expand their influence in the 12th century and in the early 16th century, they exercised control over more territory than any other people had done in South American history.
Unlike the military empires in Central America, the Incas ruled by proxy. After conquering a people, they would incorporate local rulers into their imperial system, generously reward anyone who fought for them, and treated well all those conquered people who cooperated. So, in reality, the Inca was a modern-day confederation of tribes with a single people, the Incas, more or less in control.