Quipu

A mnemonic device used by the Inca for keeping accounts and records. It consisted of a number of thick cords of various thicknesses and colors, on which numbers and other data were indicated by knots of different sizes and positions on the strings. Based on a decimal system, the color of the cord, as well as the size, configuration and placement of each knot, had a special meaning. So complex was the system that a special class of workers, quipu-camayoq (quipucamoyac), kept the imperial records on quipu. The Incas did not have writing, but quipus could also be used as aids in recording historical or liturgical information accumulated by government. A modified form is still used by some Andean herdsmen.

A cord from which was suspended a series of knotted strings, used by the Inca as a record-keeping or mnemonic device. Based on a decimal system, the colour of the cord, as well as the size, configuration and placement of each knot, had a special meaning. So complex was the system that a special professional class (the quipucamoyac) grew up to interpret meaning. Used mostly for imperial accounting, the quipu may also have been employed to record cultural and historic data; a modified form is still used by some Andean herdsmen.