Quipus or Khipus was a system used by the Incas for keeping records and sending messages. The Quipu, which is believed to have come before the rise of the Inca, was based on a decimal system. Small knotted strings were attached to a main cord or top band to symbolize a message. The color of the string, its place, its size and the knots in it were all important for the record or message. The quipus had to be made up and interpreted by trained officials. Some Andean shepherds still use a similar method of quipu, but the original method of deciphering it is not known today.
An example of a quipu from the Inca Empire, currently in the Larco Museum Collection.