Who made these knotted records during the Inca Empire?

A cotton and agave fiber Inca khipu is seen at an exhibit at the Smithsonian National Museum of the American Indian in 2015 in Washington, D.C.

Inca society kept records by encoding information into knotted cords called khipu. A new analysis of hair woven into these cords suggests this record-keeping was practiced by commoners as well as elites.

(Image credit: Brendan Smialowski)