A remote mountainside in southern Peru known as Monte Sierpe contains roughly 5,200 enigmatic holes, long puzzling archaeologists, but new research reported by Live Science offers clues to their purpose. The holes, arranged in a continuous band nearly a mile long and split into blocks of tens of divots, may have been used as a marketplace and accounting system hundreds of years ago. Each hole measures between 3 to 6 feet across and up to 3 feet deep, with some lined with rocks, and the site is located near an ancient defensive settlement and pre-Hispanic road junction.
Archaeologists first documented the site in the 1930s, with a more detailed survey in the 1970s, but it has remained largely unstudied due to its isolated location. Over the years, researchers proposed multiple theories for the holes, ranging from defense and storage to water collection, fog capture, or gardening.
In the new study, published Nov. 10 in the journal Antiquity, researchers employed drones to capture high-resolution aerial imagery and analyzed sediment and rock samples from several holes. The team, including study co-authors Charles Stanish of the University of South Florida and Jacob Bongers of the University of Sydney, discovered pollen from maize and bulrush, suggesting that the holes once held crops, plant materials, and other goods transported in baskets. Maize pollen does not naturally disperse far, indicating human placement, while bulrush was historically used for weaving containers in Chincha society.
The drone analysis revealed that the arrangement of holes mirrored the structure of Incan khipus, knotted cords used for record-keeping. Slight variations in the number of holes per block may have represented different tribute amounts from surrounding communities. The study proposes that Monte Sierpe functioned as a barter hub along regional trade routes, with goods and tribute carefully organized and counted in a system similar to early Andean accounting practices.
“This study contributes an important Andean case study on how past communities modified landscapes to bring people together and promote interaction,” Bongers said. “Our findings expand our understanding of barter marketplaces and the origins and diversity of Indigenous accounting practices within and beyond the ancient Andes.”
By combining drone imagery with archaeological sampling, researchers are shedding light on a centuries-old mystery, revealing that Monte Sierpe was likely far more than a collection of holes — it was a bustling center of trade, exchange, and record-keeping in the pre-Hispanic Andes.
