The Quipu
The Quipu was a system of knotted cords used by the Incas and its predecessor societies in the Andean region to store massive amounts of information important to their culture and civilization.

Quipu is the Spanish spelling and the most common spelling in English. Khipu is the word for "knot" in Cusco Quechua (the native Inca language).

Video Description
Mysteries Woven Into Peru's Past by Simon Romero and Meridith Kohut for The New York Times.

San Cristobal de Rapaz’s isolation has allowed it to guard an enduring archaeological mystery: a collection of khipus or quipu. Rapaz, home to about 500 people who subsist by herding llamas and cattle and farming crops like rye, offers a rare glimpse into the role of khipus during the Inca Empire and long afterward. The village houses one of the last known khipu collections still in ritual use.

The ability of Rapacinos, as the villagers are called, to decipher their khipus seems to have faded with elders who died long ago, though scholars say the village’s use of khipus may have continued into the 19th century. Testing tends to show dates for Rapaz’s khipus that are well beyond the vanquishing of the Incas, and experts say they differ greatly from Inca-designed khipus.
Read more at NYTimes.com San Cristobal de Rapaz Journal