Science Decoding the mystery of 5,200 giant round holes in Peru, once believed to be a UFO landing site (Dan Tri) — This is Monte Sierpe, also known as the Strip of Holes, a structure with about 5,200 evenly spaced round holes arranged in long rows on the mountainside. Báo Dân trí•24/11/2025 News 0 A strip of holes stretching nearly 1.5 km (0.9 mi) on the barren hillsides of Pisco Valley, southern Peru, has puzzled scientists for nearly a century. First recorded in aerial photographs in 1933, the strange and regular arrangement of thousands of pits has become one of the greatest mysteries of Peruvian archaeology. For decades, theories have ranged from defensive fortifications to ancient tombs to alien landing sites. But a newly published study has revealed the long-awaited solution. One of thousands of circular holes at Monte Sierpe (Photo: Charles Stanish). The pre-Inca market and the giant accounting system of the Incas The new study, published in the journal Antiquity , by a team led by archaeologist Jacob Bongers of the University of Sydney, used drone mapping techniques combined with microscopic analysis of soil from the pits. The results suggest that Monte Sierpe may have been a large pre-Inca marketplace, and later used by the Incas as a giant open-air accounting system. Bongers believes that this could be direct evidence that ancient people organized the exchange of goods and managed tribute in a way completely different from our imagination. Monte Sierpe's geography was not suited to agriculture or settlement. It was dry, desolate, and almost devoid of life. Yet the 5,200 circular holes, each one to two meters wide and about a meter deep, are arranged with remarkable uniformity into about 60 clusters, each with repeating numerical patterns. The drone map shows that some clusters consist of nine consecutive rows of eight holes each, while others alternate between rows of seven and eight holes. The thousands of circular pits at Monte Sierpe are divided into groups or blocks (Photo: JL Bongers). These patterns show a clear intention in the layout and organization of the entire area. Some pits were lined with stones, others were left open, and between rows of pits were narrow corridors that are believed to have been used by people and llamas to transport goods. Trade traces and tribute management Radiocarbon dating of charcoal in a pit suggests that Monte Sierpe likely dates from around 1320 to 1405 AD, predating the rise of the Inca Empire. At the time, the area belonged to the Chincha Kingdom, a civilization known for its maritime trade, sophisticated agriculture, and llama caravans across the Andes. According to Bongers, Monte Sierpe's location was at the intersection of trade routes connecting the highlands and the coast, and between the two major Inca administrative centers of Tambo Colorado and Lima La Vieja. This suggests that it may have been a large-scale transit station for goods. When the Incas incorporated the Chincha into their empire in the 15th century, they may have taken over and developed Monte Sierpe into a system of organizing and managing tribute. The entire structure consists of about 5,200 strange circular holes (Photo: C. Stanish) Microscopic analysis of soil from many pits revealed traces of pollen and starch from important crops such as maize, amaranth, peppers, squash and sweet potatoes. There were also sedges and willows, typical materials used for basket weaving. These traces are unlikely to have been created naturally by the wind, but are more likely to have been brought by humans during the exchange of goods. The researchers believe that the ancients may have used large bundles or baskets tied and loaded onto the backs of llamas, then placed in the pits as a form of storage and classification. The Inca "Giant Spreadsheet" Another notable discovery is that the structure of Monte Sierpe bears many similarities to the khipu – an Inca knotted string recording device. Khipu were used to record important information such as taxes, censuses, and agricultural yields. A khipu found nearby shows it to have about 80 string clusters, a number very close to the approximately 60 pit clusters at Monte Sierpe. Khipu found in the same area as Monte Sierpe shows some similarities to Monte Sierpe (Photo: Claudia Obrocki). This opens up the hypothesis that the pits here may have acted as a giant spreadsheet, where each community or clan placed goods in an allocated area for Inca administrators to monitor and collect. Bongers argues that the system was a unique form of social engineering. Although they lacked writing like other Asian or Middle Eastern civilizations, the Incas used earth, stone, and geometric structures to create an efficient model for managing goods and populations. It may be a testament to the remarkable organizational abilities of Andean civilizations, which relied on the terrain and primitive tools to run a vast empire. Monte Sierpe has been the subject of many bizarre theories, from defensive fortifications to UFO landing sites. But recent research has brought the story back to the reality of ancient human life. The authors argue that this work is a clear example of how Andean communities have transformed the landscape to unite communities and enhance interactions between different groups of people. However, Monte Sierpe still has many unsolved mysteries: why the structure was designed according to such unique numerical models, and why this area is the only place to have such large-scale construction. Source: https://dantri.com.vn/khoa-hoc/giai-ma-bi-an-5200-ho-tron-khong-lo-o-peru-tung-duoc-cho-la-bai-dap-ufo-20251120033054679.htm Source: https://www.vietnam.vn/en/giai-ma-bi-an-5-200-ho-tron-khong-lo-o-peru-tung-duoc-cho-la-bai-dap-ufo