The original Incan state originated around the 12th century in Peru. The Incans created their empire by conquest starting in the early 15th century and in about 100 years conquered the entire western coast of South America before being conquered by the Spanish in 1532. One of the ways the Incans controlled large populations was to displace many of them to other parts of the empire (This sounds a lot like the system the Babylonians used to control the Levant and the Jewish population during the Babylonian Captivity). Macchu Picchu was not a typical city and it was only occupied for less than 100 years starting around 1460 AD. The Incans conquered and controlled this vast empire using a small knotted string system for use in accounting but they never developed a writing system.

(The Great Courses – The Origin of Civilization)