Researchers from the University of Sydney have uncovered new evidence that might solve one of South America’s most enduring archaeological puzzles—the “Band of Holes,” an almost one mile stretch of more than 5,000 circular depressions carved into the desert hills of Peru’s Pisco Valley.
According to Science Daily, a study published on November 10 in Antiquity, suggests that the site, formally known as Monte Sierpe (“serpent mountain”), may have functioned as a large pre-Inca trading center that was later adapted by the Inca Empire into a sophisticated accounting system.
Using high-resolution drone mapping and soil analysis, the study’s lead author Jacob Bongers, a digital archaeologist at the University of Sydney, and his team identified geometric patterns in the holes that mirror the structure of knotted-string recording devices called khipus that the Inca used to track goods and tribute.
Soil samples revealed traces of maize and reeds—materials used in food and weaving—indicating the holes once held plant products, perhaps in baskets. Bongers believes this points to a pre-Hispanic marketplace frequented by traders, farmers, and fisherfolk who exchanged regional goods such as corn and cotton.
“This is an extraordinary discovery that expands understandings about the origins and diversity of Indigenous accounting practices within and beyond the Andes,” Bongers told Science Daily.
The research marks the most detailed scientific study of Monte Sierpe since the 1930s, when aerial photographs first brought it to global attention. Drone imagery revealed deliberate segmentation and symmetry invisible from ground level due to the region’s constant haze.
“Fundamentally, I view these holes as a type of social technology that brought people together,” he said. “Later, under the Inca, they may have become a large-scale accounting system.”
Monte Sierpe lies between two Inca administrative centers and at the crossroads of major pre-Hispanic trade routes, reinforcing the interpretation of the site as a hub of barter and redistribution.
“Once we had precision, low-altitude images it was immediately clear this site was profoundly important,” the study’s co-author, Professor Charles Stanish of the University of South Florida told Science Daily. “The new data debunk decades of pseudo-archaeological speculation and reaffirm Indigenous innovation in landscape design and exchange.”
