A groundbreaking study published in Antiquity has shed new light on the purpose of the enigmatic site known as the “Band of Holes” on Monte Sierpe in southern Peru.
The research, led by archaeologist Jacob L. Bongers and his team, argues that the 1.5-kilometre-long series of over 5,000 precisely aligned holes served as a sophisticated Indigenous system of accounting and exchange.
Situated in the Pisco Valley’s foothills and once part of the territory of the pre-Hispanic Chincha Kingdom, Monte Sierpe has long been a source of speculation.
Earlier theories suggested defensive works, mining activity, or water collection, but the new study uses drone imagery and micro-botanical sediment analyses to propose a compelling alternative: the site functioned first as a barter marketplace and later as part of the Inca Empire’s tribute accounting system.
The holes are arranged in segmented blocks, some in simple rows, others with alternating patterns, indicating deliberate numerical organisation. One section features nine consecutive rows of eight holes; another alternates between seven and eight holes across twelve rows. These layouts resemble the structure of an Inca khipu, a knotted-string recording device, suggesting a shared conceptual logic of counting and record-keeping.
Microscopic botanical analysis revealed pollen, phytoliths, and starch grains of maize, cotton, chili, and other crops inside the holes. The presence of these traces supports the idea that goods were deposited within them for exchange or tribute collection.
Researchers propose that Monte Sierpe operated in two distinct phases. During the Late Intermediate Period (AD 1000–1400), it likely served as a regional barter venue where agricultural producers traded maize, cotton, and other commodities along major trade routes.
Later, under Inca rule (after AD 1400), the site appears to have been integrated into the imperial economy, functioning as a registry for tribute-in-kind, with each section of holes possibly representing particular kin-based units or administrative groups.
The findings challenge long-held assumptions that pre-Hispanic Andean societies lacked formal marketplaces and accounting systems. Instead, they reveal a complex Indigenous system of quantification, exchange, and organisation predating European contact by centuries.
The study also demonstrates how landscape architecture can embody economic and social logic, showing that the terrain itself at Monte Sierpe was designed to reflect both spatial and numerical order.
Header Image Credit : American Natural History Museum; AMNH Library
Sources : Antiquity
