An information device used in the Incan Empire and other ancient Andean cultures in which colored, knotted strings were used to record numbers and categories of things and 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.