Well the Incas made some great contributions to history. One way was that they made quipus. Even thought the Incas did not have a written language they did use quipus, which were a complex math and communication system. Quipu strings were very effective and they helped with math and communication all throughout the Inca empire. The Inca people also built roads, stone buildings, and developed different ways of farming. They also discovered many things about astronomy. I sure hope this helps! :)
