With no written language, the Inca devised a tool for recording the movement of people and goods.

The quipu is a series of colored, knotted strings. The type of knot indicated a number, and the knot’s placement signified units of 1, 10, 100, or more. All the cords hung from a main string, and their positions and colors likely signaled what was being counted—gold, corn, or other goods.