They were probably one of the few developed ancient civilizations that did not communicate with writing (because they did not know it) but had an alternative way to store communication called the "Quipus."
The Inca Empire covered a very large geographical area, in fact, the largest in the Americas, and included countries such as Colombia, Ecuador, Peru, Bolivia, Chile, and Argentina. They had a very developed system of canals and aqueducts that provided irrigation and filtered water to their population. They were probably one of the few developed ancient civilizations that did not communicate with writing (because they did not know it) but had an alternative way to store communication called the "Quipus." Their constructions, which are still standing, are out of this world.