Khipu

The khipu (or quipu, an older orthographic rendering of the Quechua word for "knot") were recording devices used used in the Inka empire and its predecessor societies in the Andean region of South America. A khipu usually consists of colored cotton cords with numeric values encoded by knots in the base-10 positional system. Use of the khipu was suppressed after the early 16th century conquest of the Inka empire by the Spanish conquistadors, but more primitive uses of the khipu survive in the Peruvian highlands.