A communication and information-storage device used in the Inca Empire and other ancient Andean cultures. Quipu consisted of  colored, knotted strings that were used to record numbers and categories of people and commodities, and also narrative accounts. (Also spelled khipu). Web resources here and  here. Video here.

Quipu from Ayacucho, Peru. Cotton. 1300-1532 CE. Museo Arqueológico Rafael Larco Herrera, Lima, Perú.