Question

How did the Inca Empire manage to function without a system of writing?

Answer 1

Used a quipu for communication--a quipu is a knot-quilt with each knot or string of knots representing a symbol or number. 

Between the verbal language of the Incas and the quipu, they were able to communicate. The quipu was used to keep records and communicate information through the empire. 

Answer 2

The Inca had absolutely no form of writing whatsoever. So they didn't know how to write anything. This was a problem so they had to invent other ways to kind of keep track of records and other important things.

As a result, the Aztecs used quipu.

Quipu was a mathematical system and it was commonly used throughout the Inca empire to record and transmit data. So, the fact that they were able to get around this huge barrier is pretty amazing.