Peru is filled with archaeological sites and wonders: Caral, the Nazca Lines, Sacsayhuaman and Machu Picchu, just to name a few. Many aspects of these sites remain mysteries to us today, not least because of the lack of written language in Andean cultures (records were primarily kept through the still-not-completely deciphered knotted cords known as khipus).
A lesser known site, but one which has certainly remained mysterious, is the ‘Band of Holes‘ at Monte Sierpe (“serpent mountain”) on the Nazca Plateau, comprised of up to 6,000 neatly arranged holes that run for around 1.5km (almost a mile). Each hole is about 1 metre in diameter, and of similar depth. Their intended use has remained a mystery; theories about their use have included that they were defensive positions, graves, or storage pits.
However, a new detailed analysis of the site published recently in the journal Antiquity has suggested that the thousands of holes might actually have served as a ‘tax spreadsheet’ for the Inca. As reported at Nautilus, when the researchers looked at the Band of Holes using drone imagery, they noticed that the holes were grouped into at least 60 sections, and also spotted numerical patterns in these sections. For example, one section has nine consecutive rows with eight holes each, while another has east 12 rows that alternate between counts of seven and eight holes, hinting at “an underlying intention in the organisation of Monte Sierpe”:
This reminded them of another Inca invention: khipus, Inca accounting tools made of knotted string that were used to tally information including census data and tribute taxes. Researchers have found more than 1,000 surviving khipus, and one discovered near Monte Sierpe shows similar organization of data into 80 groups of cords.
“The regularity of these squares is comparable to the numerical patterns at Monte Sierpe, suggesting a potentially similar purpose: the counting and sorting of different goods,” the paper notes.
The Band of Holes sits near the intersection of busy ancient trade routes, as well as being located between two Inca administrative centers, which led researchers to considering a possible link with trade and government affairs.
These thousands of holes may have been turned into a spreadsheet after the Inca Empire took over the area in the 15th century, which was previously ruled by the powerful and sophisticated Chincha Kingdom. As in other areas, the Inca introduced a tax system that demanded labor or tribute, such as produce.
At Monte Sierpe, each section of holes may have been “linked to a particular social group for the payment of tax and the redistribution of commodities,” the new paper suggests. The range of numerical patterns they observed might be linked to local khipus and 16th-century tribute lists in the Andes, and the size of taxpaying populations may have varied among specific towns and villages.
Confounding this theory was unexpected evidence from sediment samples taken from the holes, which revealed ancient pollen from plants such as willow (traditionally incorporated into baskets and mats), and from corn, suggesting that baskets of foods and goods may have been placed in them. The authors of the new study therefore hypothesise “that Monte Sierpe initially served as a barter marketplace before being turned into a large-scale accounting device under the Inca Empire (1400–1532 AD) for collecting tribute from local communities.”
The researchers make clear that their model “remains tentative”, but all the same “our research brings us closer to unravelling the purpose behind one of the most enigmatic archaeological sites in the Andes.”
