For almost a hundred years, those involved in archeology have been looking at the Mount Sierpe in Peru with the same question: Why do thousands of potholes, aligned with almost geometric precision, cover an entire hill in the Pisco Valley? They are about 5,200distributed along a 1.5 kilometer band. From afar it looks like a scar running across the landscape. Up close, it is a work that resembles nothing else.
Now a new study published on Antiquities proposes a much more concrete answer — and, in its way, more fascinating than the theories that have circulated so far. According to a group of Australian, American and Peruvian researchers, Monte Sierpe would have been a place of exchangea meeting point between different communities, previously used as barter market and then how administrative space by the Incas, who transformed it into a system for recording tributes and quantities of goods.
What the latest data collected on the site shows
The team flew over the hill with high-precision drones, useful even in the presence of fog that often covers the area. The images revealed that the potholes are not randomly distributed: they are organized into sections with repeating number patternssuch as rows of eight holes or sequences alternating between seven and eight holes.
This regularity closely recalls the logic of khiputhe knotted ropes used by the Inca to record administrative data. It’s as if, centuries ago, someone had turned the entire hillside into a large physical archivedivided into compartments.
Laboratory analyzes have added a fundamental piece. Inside the holes were found remains of corn, pumpkins, amaranth, fiber plants and even pollen transported in plant baskets and bundles. They are not species that grow spontaneously on the hill: they were brought there.
Radiocarbon dating places some of the use of the site between 1320 and 1405 ADtherefore in the middle of the Chincha period, before the Inca expansion.
A meeting point between the coast and the Andes
Monte Sierpe is located in an area called chaupiyungaa natural passage between the Pacific coast and the Andes. In pre-Hispanic times it was a strategic point:
The Kingdom of the Chinchawhich controlled the area between 1000 and 1400 AD, was a very organized society: approximately 100,000 peopleadvanced agriculture (also thanks to the guano used as fertilizer), specialized artisans and a strong commercial network.
In this context, it is not surprising that Monte Sierpe was a barter market. The holes would have functioned as orderly spaces to store goods and organize exchanges between different groups.
When the Incas conquered the region in the 15th century, the site changed function: from market to place to register tributes and redistribute productsalways following a numerical order consistent with their administrative system.
For years, Monte Sierpe has been associated with fanciful theories. The study instead manages to give a more solid and respectful reading of the work of local populations. The potholes become the concrete trace of how these communities organized the territory, exchanges and management of resourceswithout resorting to written tools but with systems that are shared and understandable to all.
The research will continue with new excavations, other sediment analyzes and comparisons with the khipu preserved in museums. The objective is to reconstruct with ever greater precision how this seemingly simple place played a fundamental role in the daily lives of the people who used it.
