Quipu
The quipu, or khipu, is the knotted-cord record-keeping system of the Andes, in which a main cord holds pendant cords whose colours, knot positions and spacings encode information, read by trained officials known as khipu-kamayuq. The Inca empire used quipus to keep accounts of tribute, census, harvests, armies, calendars and storerooms, and Spanish chroniclers called them the 'books' of the empire, records the colonial government could not match. Scholars have shown that the knots encode numbers in a decimal positional system, and a growing minority argues some quipus also carried narrative a