Quipu
Quipu ( KEE-poo), also spelled khipu (Ayacucho Quechua: kipu, [ˈkipu]; Cusco Quechua: khipu, [kʰipu]), are record-keeping devices fashioned from knotted cords. They were historically used by various cultures in the central Andes of South America, most prominently by the Inca Empire.