Monte Sierpe, meaning “Mountain of the Serpent” and informally referred to as the “Zone of Holes,” is situated in the Pisco Valley of southern Peru. It comprises around 5,200 meticulously aligned holes. Recent studies indicate that the site may have originally functioned as a barter market, bringing together a variety of people for trade.

Stretching over 1.5 km in the Pisco Valley of the southern Peruvian Andes, Monte Sierpe features approximately 5,200 carefully aligned holes (ranging from 1–2 m in width and 0.5–1 m in depth) arranged in distinct sections.

This extraordinary structure likely dates back to at least the Late Middle Period (1000-1400 AD) and was actively used by the Incas (1400-1532 AD).

Initially brought to modern attention in 1933 following an aerial photo published in National Geographic, the specific purpose of the monument remains a mystery.

Speculations about its function include various roles such as defense, storage, accounting, water collection, fog capture, and horticulture, but the actual intent continues to elude researchers.

“What led ancient people to excavate over 5,000 holes in the hills of southern Peru? Were they used for gardens? Did they provide water? Did they serve agricultural purposes?” inquires Dr. Jacob Bongers, a digital archaeologist from the University of Sydney.

“While we cannot ascertain their purpose, our new data offers significant clues and supports emerging theories regarding the site’s utilization.”

Utilizing drone technology, Dr. Bongers and his team mapped the site, uncovering numerical patterns in its layout that indicate intentional organization.

Interestingly, the archaeologists also found that the configuration of Monte Sierpe resembles that of at least one Inca quipu (an ancient knotted string for accounting) discovered in the same valley.

“This discovery significantly enhances our understanding of the origins and variety of indigenous accounting practices both within and outside the Andes,” noted Dr. Bongers.

Soil samples taken from the holes revealed ancient maize pollen, one of the Andes’ key staple crops, along with reeds traditionally utilized for basket making for millennia.

These surprising findings indicate that ancient people likely planted crops in the holes, using woven baskets and bundles for transport.

“This is quite intriguing. Perhaps this area functioned as a pre-Inca market, akin to a flea market,” remarked Dr. Bongers.

“We estimate that the pre-Hispanic population in this region was around 100,000. It likely served as a meeting point for traveling merchants, including llama caravan traders, as well as local professionals like farmers and fishermen to trade goods like corn and cotton.”

“Fundamentally, I believe these holes served as a form of social technology that unified individuals and later evolved into a comprehensive accounting system under the Inca Empire.”

“Numerous questions remain: Why is this monument unique to this location and not found throughout the Andes?”

“Was Monte Sierpe a type of ‘landscape’? – Nevertheless, we are gradually moving closer to unraveling the mysteries of this fascinating site. It’s genuinely exciting.”

Refer to the study published in the Journal on November 10, 2025 ancient.

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Jacob L. Bongers et al. Indigenous accounting and interaction at Monte Sierpe (“Band of Holes”), Pisco Valley, Peru. ancient published online on November 10, 2025. doi: 10.15184/aqy.2025.10237