quipu

quipu [Ar].
A thick cord from which was suspended a series of knotted strings, sometimes of different colours. This was used by the Inca as a mnemonic device to keep imperial records, the position, size, colour, and position of each knot having a special meaning. A special hereditary group of state functionaries, the quipucamayocs, memorized the history, myths, and statistical information symbolized by the knots and recited them to state officials.