The Incans and (and other Andean cultures) used quipus to record data, in place of writing. In these instances, data was numbers like population size, payment amount, or livestock count. The types of knots, thread color and positions all have meaning. Quipu is the Spanish name, from the word for knot.
We saw these quipus at the Larco Museum in Lima, which holds over 40,000 Peruvian artifacts (and only 3 replicas!). Super legit.