Archaeologists excavating the 15th century Inca archaeological site of Incahuasi, about 90 miles southeast of Lima and 20 miles inland from the coast of central Peru, have found 25 quipu, groups of knotted and dyed strings tied together that were used by the Inca for keeping records. The quipu are in various shapes, sizes and configurations. The longest is two groups of strings tied together to form a row three feet wide, with an additional tail in the center where the two strands meet. The smallest is just a few inches wide, the size of a small notepad.
Quipu (also called “khipus” or “talking knots”) typically consisted of colored, spun, and plied thread or strings from llama or alpaca hair. They aided in data collection and record-keeping, including the monitoring of tax obligations, census records, calendrical information, and military organization. The cords contained numeric and other values encoded on knots in a base-10 positional system. Some quipu had as many as 2,000 cords.
In widespread use for 800 years or so in cultures that had no written language, the quipu were targeted for destruction by the Spanish conquistadors. They were collected and burned. Today only a few hundred have survived because they were used as grave goods. The Incahuasi quipu, on the other hand, were not found in a funerary context but rather unearthed in the city’s warehouses where they were used in the management of whatever was stored there, most likely agricultural products. Ceramic pots recovered from the warehouses are marked with symbols for maize and other crops.
Incahuasi was founded in 1450 by King Túpac Yupanqui who expanded the Inca empire south along the coast and established the city as an administrative and military center for the ongoing campaign against the local Huarcos people who resisted the Inca invaders. He called it New Cusco, after the Inca capital, and planned the city to be a smaller scale replica of the original. The architecture was therefore deliberately grand, meant to convey imperial power. Structures found so far include 64 circular columns, ushnu (terraced pyramids) temples, forts, soldier’s barracks, ceremonial courtyards, warehouses, grain stores on a plan of streets and squares similar to the northern capital. It’s the most important Inca archaeological site in coastal Peru.
The climate is dry, a sub-tropical desert, which required the construction of canals and irrigation systems to enable agriculture. It also preserves organic material like knotted cotton strings. Their condition is so good that conservators have been able to straighten them with a surprisingly simple method. The strings of the longest one were crimped and tangled, so curator Patricia Landa Cragg placed a damp paper towel on top of them and held a weight over it. The treatment works like a charm, as you can see in the photograph left where the strings on the left side have been straightened while the ones on the right have not. There’s video of Patricia explaining the process on this page (which is currently down but was working fine earlier). The video also shows some of the other quipu found at the site and the recovered ceramic pottery.
For more about this fascinating and complex system of 3D language (there’s some evidence quipu weren’t just used for accounting purposes, but also to record literature and mythology), see Harvard’s Khipu Database Project.