Archaeologists working in Peru have discovered 25 well-preserved quipus, an ancient string-based device used to solve mathematical problems and to assist in record-keeping.
The find was made in the archaeological complex of Incahuasi, south of Lima, Alejandro Chu, reports Peru This Week. The items were found in ancient warehouses, or kallancas, and not in a funerary context as is the norm, making this a rather unique find. The placement of the quipus suggests they were used for administrative purposes. Incahuasi was one of the most important strategic cities built by the Incas in the valley of Lunahuana.
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.
The Khipu Database Project describes quipus and how they worked:
Most of the existing khipu are from the Inka period, approx 1400 – 1532 CE. The Inka empire stretched from Ecuador through central Chile, with its heart in Cuzco, a city in the high Andes of southern Peru. Colonial documents indicate that khipu were used for record keeping and sending messages by runner throughout the empire. There are approximately 600 khipu surviving in museums and private collections around the world.
The word khipu comes from the Quechua word for "knot" and denotes both singular and plural. Khipu are textile artifacts composed of cords of cotton or occasionally camelid fiber. The cords are arranged such that there is one main cord, called a primary cord, from which many pendant cords hang. There may be additional cords attached to a pendant cord; these are termed subsidiaries. Some khipu have up to 10 or 12 levels of subsidiaries. Khipu are often displayed with the primary cord stretched horizontally, so that the pendants appear to form a curtain of parallel cords, or with the primary cord in a curve, so that the pendants radiate out from their points of attachment. When khipu were in use, they were transported and stored with the primary cord rolled into a spiral. In this configuration khipu have been compared to string mops.
Each khipu cord may have one or many knots. Leland Locke was the first to show that the knots had numerical significance. The Inkas used a decimal system of counting. Numbers of varying magnitude could be indicated by knot type and the position of the knot on its cord. Beginning in the 1970's, Marcia and Robert Ascher conducted invaluable research into the numeric significance of khipu, and developed a system of recording khipu details which is still in wide use today among khipu researchers. More recently, researchers such as Gary Urton have recognized the depth of information contained in non-numeric, structural elements of khipu.
Regrettably, many of these quipus were destroyed by the Spanish conquistadors in the 16th century, making this recent find all the more precious.
Article originally appeared on iO9.