Summarize the Inca civilization.

The Incas, an American Indian people, were originally a small tribe in the southern highlands of Peru. In less than a century, during the 1400s, they built one of the largest, most tightly controlled empires the world has ever known. ... Roads, walls, and irrigation works constructed by the Incas are still in use today.

the historians cited in the article all agree with one another about the cause of the civil war. despite coming from different backgrounds and cultures, the historians agree that slavery was the root cause of the civil war. the fact that all these historiansgenerally agree with one another makes their shared viewpoints more reliable and valid, especially because the historians have different backgrounds and all work for the well-respected institutions of howard university, clemson university, and the university of colorado.