The Incas developed a record-keeping system using knots and designs in strings.
The Incas never developed a written language but their system of record keeping called Quipu is unique in human history. Inca recorded accounts with knotted string. Quipu means knot in Quechua, the language of the Incas. However, the Inca civilization did not invent Quipu; it was used by earlier Andean cultures. Quipus have been found all over the Andes. The Incas refined Quipu to a more sophisticated level.