A quipu (also spelled khipu, and sometimes searched as “quipa”) is a recording device made of knotted cords that was used by the Inca Empire and other Andean civilizations to store information. Think of it as a kind of three-dimensional spreadsheet: a main horizontal cord with dozens or even hundreds of smaller strings hanging from it, each tied with carefully placed knots that represent numbers, categories, and possibly even words and names. Quipus were the primary tool the Inca used to run one of the largest empires in history, all without a conventional writing system.
How a Quipu Is Built
A quipu starts with a single thick cord, usually stretched horizontally, called the main cord. Hanging from it are thinner strings called pendant cords, and sometimes those pendants have their own smaller strings branching off them. The whole structure is made from natural fibers, most commonly cotton or hair from camelids like alpacas, llamas, and vicuñas. In some cases, archaeologists have found finely carved wood used as a base to anchor the cords.
Color is a critical layer of meaning. Pendant cords were dyed in different colors to distinguish categories of information. A quipu tracking the population of a province, for example, might use a separate pendant string for each social category of people. The order the pendants hang in, the direction the fibers are twisted (left-hand or right-hand), and even the type of fiber all appear to carry meaning. This makes a quipu far more than a simple tally. It’s a dense, multi-dimensional information system packed into something you could roll up and carry.
The Knot System: Math by Touch
The numerical backbone of a quipu is a base-10 system, just like the one we use today. Each pendant cord is read from bottom to top, with knot positions representing ones, tens, hundreds, thousands, and so on. Three distinct knot types do the work:
- Long knots represent the digits 2 through 9 in the ones place. The number of turns in the knot tells you the value, so a long knot with four turns means 4.
- Figure-eight knots represent the number 1 in the ones place.
- Single knots represent values in every position above the ones place: tens, hundreds, thousands, and ten thousands. The number of single knots clustered together gives the digit for that position.
So a cord showing a long knot with four turns at the bottom, five single knots above it, and four more single knots above those would read as 454. The spacing between knot clusters is what separates the place values, making it possible to distinguish 45 from 405. This system allowed the Inca to record very large, precise numbers across hundreds of cords on a single quipu.
What Quipus Were Used For
At a practical level, quipus ran the Inca Empire’s bureaucracy. They recorded census data, tax obligations, military inventories, stored goods, and administrative decrees. The Inca kept separate quipus for each province, with pendant strings tracking the number of people in each social category. This level of detail meant the empire could manage resources, labor, and tribute across thousands of miles of territory in the Andes.
But quipus almost certainly did more than count. Spanish colonial observers who witnessed the Inca system firsthand described quipus that recorded the reigns of rulers, their marriages, the lands they conquered, the buildings they built, how many years they lived, and where they died. One Spanish chronicler, Martín de Murúa, wrote that “everything that books teach and show us was got from there.” Some quipus were also sent as letters between officials, carried by relay runners across the empire’s road network.
Whether quipus encoded full language or served as sophisticated memory aids for trained readers remains one of the biggest open questions in Andean studies. Recent research has found that cord sequences of distinct colors, fiber types, and twist directions at the ends of some quipus appear to represent the names of lineage groups. This suggests the system may have been partly logosyllabic, encoding sounds or words rather than just quantities.
The Specialists Who Read Them
You couldn’t just pick up a quipu and read it. Interpreting these devices required trained specialists called quipucamayocs. These officials understood the conventions of meaning behind every knot position, color choice, cord material, and arrangement. They were the coders and analysts of the Inca world, responsible for both creating quipus and reading them back to administrators or rulers on demand. The role required years of training, and quipucamayocs were essential to every level of Inca governance, from local villages up to the imperial capital of Cusco.
Surviving Quipus Today
To date, 923 quipus have been inventoried in museum collections spread across 88 institutions in South America, North America, and Europe. UNESCO maintains a database cataloging these artifacts. Most surviving quipus date from the height of the Inca Empire (roughly 1400 to 1532 CE) or from the early decades of Spanish colonial rule, when some communities continued using them. A few quipus have also been preserved by village authorities in Peru, where they are considered sacred objects.
Cracking the Code
For decades, researchers could reliably read only the numerical content of quipus. The non-numerical dimensions, like color patterns and cord construction, remained opaque. That changed in a significant way when Manny Medrano, a Harvard undergraduate working with anthropologist Gary Urton, managed to match a set of six colonial-era quipus from Peru’s Santa Valley to a Spanish census document from the same region. By analyzing the cords’ colors and whether they were twisted in a right-hand or left-hand direction, Medrano identified which cords corresponded to which clans and individual villagers listed in the census.
This was the first confirmed instance of “reading” non-numerical information from quipu attachment knots. The work revealed not just that six clans existed in the valley, but also the social status each clan and each villager held. As Urton put it, “It’s giving the Incas their own voice.” The breakthrough depended on having a parallel written document to compare against, which is rare, so progress on other quipus remains slow. But it confirmed what Spanish observers had claimed centuries ago: quipus carried far more than numbers.