Instead, they used a “quipu”, which was a long piece of string to which a number of other colored pieces of string were attached, with knots tied in them. The colors represented specific information and the knots showed numbers. It was a complicated system, only understood by the quipu keepers, who were called quipumayocs.

Yellow strings stood for gold, white for silver, green for coca, red for soldiers, and so on. By looking at a quipu, officials could tell how many warriors they could expect from any village, the food available to feed them, and where it was stored. If there was a poor harvest in one province, they knew at a glance how much help its members could send. Knots representing births and deaths were constantly being tied and untied; quipus even recorded the ages of the population and the number of people following each occupation.