Archaeologists Decode Peru’s Monte Sierpe: A Market and Accounting System in One

Archaeologists from the University of Sydney have proposed a convincing explanation for one of South America’s most mysterious ancient sites — Monte Sierpe, a complex of more than 5,200 identical pits carved into a ridge in southern Peru. Since its discovery in 1933, the site has fascinated scientists with its scale and enigma. Now, research published in the journal Antiquity suggests that Monte Sierpe may have served a dual role — functioning both as a marketplace and a sophisticated accounting system.

The team led by archaeologist Jacob Bongers conducted drone surveys and sediment analysis of the pits. Samples revealed starch grains and pollen from maize, amaranth, cereals, and gourds, along with remnants of reeds and willow, materials once used for basket weaving. These findings indicate that the pits likely stored food and goods delivered by maritime traders and llama caravans — suggesting that the site was a bustling marketplace for the people of the Chincha culture, which thrived before the rise of the Inca Empire.

By the 15th century, when the Inca Empire expanded into the region, Monte Sierpe may have been reinterpreted and transformed into a monumental counting device. Researchers noticed that the pits form block patterns resembling the quipu — the Incas’ famous knot-based system used for tracking taxes and supplies.

According to the study, Monte Sierpe represented a unique form of social technology that combined commerce, administrative control, and ritual exchange. The structure illustrates how ancient civilizations used engineering and economic organization to transform landscapes into systems of communication.

“Monte Sierpe demonstrates the extraordinary ingenuity of ancient Andean societies, merging trade, record-keeping, and ritual into a single architectural vision,” the researchers concluded.