For nearly a century, Peru’s mysterious “Band of Holes” has puzzled archaeologists, fueling endless speculation about their mysterious purpose.
Stretching for nearly a mile across the stark hills of the Pisco Valley, the long ribbon of thousands of evenly spaced pits has been alternately described as a defensive fortification, a burial ground, a mining site, and—inevitably—as possible evidence of extraterrestrial engineering among fringe theorists.
Now, an international team led by archaeologist Dr. Jacob L. Bongers of the University of Sydney believes they have solved the mystery—and it’s far more human than cosmic.
In a new study published in Antiquity, Dr. Bongers and colleagues argue that Monte Sierpe, as the site is formally known, once served as a monumental record-keeping and exchange center, as well as an Indigenous system of accounting, that predated the arrival of Europeans by centuries.
Combining drone mapping, microbotanical analysis, and comparisons with Inca counting devices, the team suggests the site may have started as a bustling barter marketplace under the Chincha Kingdom and later evolved into a formal tribute-collection center under the Inca Empire.
“Hypotheses regarding Monte Sierpe’s purpose range from defence, storage, and accounting to water collection, fog capture, and gardening,” Dr. Bongers said in a press release. “These data support the hypothesis that during pre-Hispanic times, local groups periodically lined the holes with plant materials and deposited goods inside them, using woven baskets and/or bundles for transport.”
The site consists of approximately 5,200 circular holes, each measuring 3 to 6 feet in diameter and up to 3 feet in depth, arranged in a band that spans nearly a mile along the hills north of the Pisco Valley—a dry coastal region in southern Peru, located approximately 130 miles south of Lima.
Early theories suggested the pits might have been for grain storage, tombs, or even a military fortification. However, none of those ideas fit the data. The holes contained no human remains, no weapons, and little evidence of long-term storage.
That began to change once modern drone imaging made it possible to map the site in unprecedented detail.
“Until drone technology, the site of Monte Sierpe was extremely difficult to map on the surface,” co-author and Professor of Archaeology at the University of South Florida, Charles Stanish, explained. “Once we had precision, low-altitude images, it was immediately clear that this site was profoundly important and had to be scientifically studied.”
From above, the aerial photographs revealed something astonishing: mathematical patterns hidden in the layout of the holes. In several sections, the pits appear in repeated numerical groupings—primarily sequences of sevens and eights—suggesting intentional design rather than random excavation.
The team also collected 21 sediment samples from different holes and analyzed them for microscopic pollen, starch grains, and phytoliths. The results revealed traces of maize, squash, and bulrushes. These plants are commonly associated with trade goods, basket-making, and transportation.
Together, these findings pointed to an economic purpose.
Dr. Bongers and his colleagues proposed that the site was used by the Chincha, a prosperous coastal kingdom that dominated the region between A.D. 1000 and 1400. Historical records describe the Chincha as expert merchants who traded along both land and sea routes, connecting coastal and highland communities.
Monte Sierpe’s strategic position—near a crossroads of ancient trade routes and between the Inca administrative centers of Tambo Colorado and Lima La Vieja—made it an ideal place for exchange.
“The Chincha Kingdom was reportedly composed of economic specialists, with at least 10,000 fisherfolk, 10,000 farmers, and 6000 artisans and merchants living in distinct parts of the Chincha Valley,” researchers note. “Alongside permanent fisherfolk and farming communities, Chincha merchants substantially expanded interregional trade networks and became a valuable source of wealth for the kingdom.”
The researchers propose that the Band of Holes initially functioned as a barter marketplace under the Chincha Kingdom, where locally grown goods such as maize and cotton were exchanged among nearby communities. The holes may have served as temporary receptacles, allowing traders to deposit or organize goods in a structured, ritualized setting.
Later, after the Inca incorporated the Chincha Kingdom into their empire in the 15th century, Monte Sierpe’s function appears to have shifted. Its segmented layout—blocks of holes separated by open spaces—resembles the structure of Inca khipus, the knotted-string devices used to record census information, tribute, and inventories.
One such khipu, found near Pisco and now housed in Berlin’s Ethnological Museum, shares a nearly identical pattern of grouped numerical sequences to those observed at Monte Sierpe.
The authors propose that under Inca rule, Monte Sierpe served as a large-scale accounting space for the collection and redistribution of tribute. Each section may have corresponded to a social group responsible for depositing goods—such as maize—into the holes, echoing the organizational logic of Inca khipus used to record census and tribute data.
Much like the nearby Nazca Lines, Monte Sierpe has been a favorite target of fringe “ancient astronaut” theories for decades, with claims that its thousands of holes were alien landing sites or remnants of extraterrestrial mining. Dr. Stanish says the new findings help restore the site’s true cultural significance.
“The site has always been very prominent in the pseudo-archaeology world with rampant speculation and mischaracterization of the data on the ground,” Dr. Stanish said. “One of the benefits of scientific work is the debunking of unsubstantiated claims that in many ways deprive Indigenous peoples of their rightful ownership of their past.”
By demonstrating that Monte Sierpe was part of a homegrown Andean information system, the study not only clarifies its earthly origins but also highlights the sophistication of Indigenous knowledge long before European contact.
“This study contributes an important Andean case study on how past communities modified landscapes to bring people together and promote interaction,” Dr. Bongers added. “Our findings expand our understanding of barter marketplaces and the origins and diversity of Indigenous accounting practices within and beyond the ancient Andes.”
The discovery has broad implications for how archaeologists understand pre-Columbian economies. As the study notes, Indigenous societies, such as the Chincha and Inca, developed sophisticated systems of numeracy, logistics, and record-keeping to manage complex regional networks of exchange. Significantly, they achieved this type of administrative precision without a written alphabet.
By identifying a site that may have functioned as both a marketplace and a state-run accounting complex, the research provides tangible evidence that the Andean world operated on shared principles of value and reciprocity, managed through communal systems rather than coin or currency.
Yet, for all the precision now visible in Monte Sierpe’s design, many questions remain. Dr. Stanish notes that future work will delve deeper into the plant remains and distribution patterns across the site.
“Now that we have established that this site was for storage and redistribution, our USF team will conduct additional work to determine the range and origins of the various plants, particularly the medicinal ones,” Dr. Stanish said. “With every identification of a new plant type, the Band of Holes becomes more intriguing.”
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com