The Incas were a distinct people with a distinct language living in a highland center, Cuzco. They were an ancient people, but had been subject to the regional powers during the entire history of South American urban cultures. They began to expand their influence in the twelfth century and in the early sixteenth century, they exercised control over more territory than any other people had done in South American history. The empire consisted of over one million individuals, spanning a territory stretching from Ecuador to northern Chile.

   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 "empire," as the invading Spanish called it, was not really an empire. It was more of a confederation of tribes with a single people, the Incas, more or less in control. Each of these tribes was ruled independently by a council of elders; the tribe as a whole gave its allegiance to the ruler, or "Inca." The "Inca" was divine; he was the descendant of the sun-god.

   The social structure of the Incas was extremely inflexible. At the top was the Inca who exercised, theoretically, absolute power. Below the Inca was the royal family which consisted of the Inca's immediate family, concubines, and all his children. This royal family was a ruling aristocracy. Each tribe had tribal heads; each clan in each tribe had clan heads. At the very bottom were the common people who were all grouped in squads of ten people each with a single "boss." The social unit, then, was primarily based on cooperation and communality. This guaranteed that there would always be enough for everyone; but the centralization of authority meant that there was no chance of individual advancement (which was not valued). It also meant that the system depended too much on the centralized authority; once the invading Spanish seized the Inca and the ruling family, they were able to conquer the Inca territories with lightening speed. Conquered people were required to pay a labor tax (mita ) to the state; with this labor tax, the Incas built an astonishing network of roads and terraced farmlands throughout the Andes.

   Agriculture was tough business in the Andes. The Incas actively set about carving up mountains into terraced farmlands—so successful were they in turning steep mountainsides into terraced farms, that in 1500 there was more land in cultivation in the Andean highlands then there is today. The Incas cultivated corn and potatoes, and raised llama and alpaca for food and for labor.

   Of all the urbanized people of the Americas, the Incas were the most brilliant engineers. The Huari-Tiahuanaco performed amazing feats of fitting gigantic stones together, and the Nazca designed mind-numbingly huge earth-drawings that still exist today. But the Inca built massive forts with stone slabs so perfectly cut that they didn't require mortar—and they're still standing today in near-perfect condition. They built roads through the mountains from Ecuador to Chile with tunnels and bridges. They also built aqueducts to their cities as the Romans had. And of all ancient peoples, they were the most advanced in medicine and surgery.

   The language they spoke was Quechua which they imposed on all the peoples they conquered. Because of this, Quechua is still spoken among large numbers of Native Americans throughout the Andes. They had no writing system at all, but they kept records on various colored knotted cords, or quipu .

   The central god of the Incan religion was the sun-god, the only god that had temples built for him. The sun-god was the father of the royal family. There were many gods among the Incas, but the sun-god outshone them all. The Incas also believed that there was a heaven, a hell, and a resurrection of the body after death.

   At its height, the Inca civilization crashed into the European expansion. In 1521, Herman Cortés conquered the Aztecs; this conquest inspired Francisco Pizzarro to invade the Incas in 1531. He only had two hundred soldiers, barely enough to walk the dog. However, he convinced the ruler of the Incas, Atahualpa, to come to a conference at the city of Cajamarca. When Atahualpa arrived, Pizzarro kidnapped him and killed several hundred of his family and followers. Atahualpa tried to ransom himself, but Pizzarro tried to use him as a puppet ruler. When that failed, Pizzarro simply executed him in 1533. Over the next thirty years the Spanish struggled against various insurrections, but, with the help of native allies, they finally gained control of the Inca empire in the 1560's.