For nearly a century, Peru’s enigmatic Monte Sierpe — known as Serpent Mountain due to its sinuous shape — has puzzled archaeologists and captured imaginations. A massive line of thousands of holes carved into an Andean ridge, it sparked theories ranging from extraterrestrial design to elaborate water collection systems. Now, new research suggests a more grounded explanation: Serpent Mountain served as both a bustling pre-Inca market and later transformed into an intricate system for collecting Inca taxes.
The Band of Holes, as this 1.5 kilometer earthwork is also called, came to prominence when National Geographic published aerial photos in 1933. Speculation about its purpose ran rampant – defense against invaders, ritualistic significance, even storage for astronomical observations. Some even suggested alien intervention.
The recent study, published in the journal Antiquity, offers a compelling alternative. Leading archaeologist Jacob Bongers of the University of Sydney and his team analyzed plant remains and radiocarbon dating from samples found within the holes. They discovered remnants of maize and wild plants used for basketry, pointing towards trade in agricultural goods around the 1300s during the rule of the Chincha Kingdom.
Located strategically at a crossroads of ancient trade routes, Monte Sierpe would have been ideal for bartering. Bongers proposes that traders from both coastal plains and highland valleys might have deposited their goods – maize in one hole, cotton in another – effectively creating a system of complex bartering based on quantities held within specific holes.
When the Inca conquered the Chincha Kingdom, the site took on a new function: tax collection. By analyzing drone imagery, researchers found that the 5,200-plus holes were organized into distinct sections separated by empty spaces. These sections displayed different construction styles and corresponded to numerical patterns found in Inca knotted record-keeping devices called khipus.
These intricate knot systems, along with Spanish accounts from the 16th century detailing Inca tribute lists, suggest that each section of Monte Sierpe might have represented a specific local community group responsible for depositing goods as tax payments. This interpretation aligns with archaeological evidence showing varying construction methods within the different sections.
“Monte Sierpe’s hole arrangements may also align with Inca tribute lists for Andes communities recorded in the 16th century by Spaniards,” explains Bongers. “Each segment corresponded to a local kin or community group, suggesting these groups took turns maintaining the thousands of holes and depositing goods into their respective sections as part of the Inca tribute system.”
The study firmly places Monte Sierpe within the context of both pre-Inca trade networks and the sophisticated administrative systems employed by the Inca Empire. By weaving together plant remains, architectural analysis, and historical records, Bongers’ team dismantles outlandish theories and offers a compelling narrative about how this enigmatic site evolved from a market to a vital cog in the Inca tax machine. This discovery sheds light not only on the ingenuity of ancient Andean societies but also highlights the enduring legacy of their complex socio-economic structures.
