Across a high slope of the Andes, 5,200 pits march in careful rows, daring any easy answer. After years of debate, researchers say a consistent explanation is within reach—and it changes how we read this landscape. Fresh analysis points to intent, not chance, and the pattern rings with human order. The mystery holes feel less like ruins and more like a system, built to be read. What it meant in practice is the question this new study confronts.
Setting, scale, and the band on Serpent Mountain
On Monte Sierpe in southern Peru, a long band of pits climbs a ridge. Known as the Band of Holes, it runs about 0.9 miles along the slope. Rows and blocks appear with intent, near old routes and a nearby defensive settlement. The pattern feels planned. It feels ancient.
Each pit spans three to six feet across and drops up to three feet deep. Several are neatly lined with stones, which adds stability and a crafted look. Archaeologists recorded the place in the 1930s and surveyed parts again in the 1970s. Its isolation spared it from development.
Construction likely falls between A.D. 1000 and 1400, within the powerful Chincha realm. This kingdom exceeded one hundred thousand people and ran coastal trade across valleys and ports. After the fifteenth-century Inca conquest, officials may have repurposed the site for tribute and taxes. Power and exchange converged here.
How the mystery holes align with barter and record-keeping
Drone surveys revealed striking patterning across modular blocks. Sections group neatly while counts vary, so the layout reads like accounts. Researchers say such order matches how people track goods during market days. The mystery holes could map stock or dues per block. That logic fits plazas used for exchange.
Barter markets thrived in the Andes, since communities traded maize, fish, and textiles. Monte Sierpe lies near intersecting roads that carried caravans before Hispanic rule. Traffic moved goods inland, while coastal valleys supplied baskets, bulrush mats, and woven cord. The setting suits a marketplace. Access mattered.
After Inca conquest, officials likely used blocks to tally tribute and tax deliveries. Minor differences in numbers across sections could match quotas owed by nearby towns. This logic fits Inca storage systems, because managers sorted food and tools by category. Audits then follow a visible path. Enforcement becomes simple.
Traces inside the mystery holes point to goods and handling
Sediment samples preserved pollen from maize, which rarely travels far without human help. That signal suggests people placed plant matter inside the pits during busy exchanges. It grounds talk of the mystery holes in practice, not in myth or guesswork. Evidence narrows the options. Purpose gains clarity.
Bulrush pollen appears too, and Chincha weavers used bulrush to craft strong baskets. Researchers argue people lined pits with fibers and set goods in woven containers. Bundles resist damp soil, while liners protect seeds, textiles, and shell or metal items. Handling stays cleaner and quicker. Turnover improves.
The team published findings on November 10 in Antiquity. Co-authors Charles Stanish and Jacob Bongers led analyses from South Florida and Sydney. They emphasized the site’s isolation, which spared it from modern development pressure. Records date to the 1930s, with further study in the 1970s. Access stays limited.
Patterns, khipus, and the logic of tribute accounting
The pattern mirrors the logic behind khipus, those knotted cords used for records. Managers grouped cords by category, while knots flagged quantities, duties, and deliveries. At storage hubs, grids helped clerks count and sort maize, fishmeal, and textiles. The layout at Monte Sierpe reads the same. The echo is clear.
Counts differ slightly across blocks, which could reflect quotas owed by local towns. Clerks note deliveries as the mystery holes fill, then stop when the target is met. Such a system ties storage to authority, yet it stays legible even at distance. Compliance becomes visible and hard to dispute.
The band runs near road intersections, so traders meet where movement already concentrates. Crossroads reduce friction, since caravans arrive without detours. Bongers argues the landscape itself invited exchange and interaction across communities. Infrastructure shapes behavior and record-keeping. Power then follows the flow. Markets thrive under such design.
Debate, alternative uses, and what remains unresolved
Scholars have floated other ideas, including defense, storage, gardening, water collection, and fog capture. The chin of the ridge looks strategic, yet the regular blocks suggest another story. Evidence now leans toward trade and counting, while the mystery holes still guard details. Function may have shifted over centuries.
Because the site is isolated, researchers never faced bulldozers or power lines here. Stanish noted there was little urgency, which slowed work but preserved context. Clean surfaces still help mapping and sampling. Intact rock linings and sediments keep clues readable. Preservation here supports patient work. Funding will decide pace.
The case expands how we see Indigenous accounting, both inside and beyond the Andes. Physical grids, khipus, and social exchange tie together, while markets leave durable signatures. By reading landscape like a ledger, the mystery holes make movement and obligation visible. Archaeology then connects practice to power.
What this Andean puzzle could still reveal about power
Evidence now stacks into a coherent picture, yet room remains for surprises. Drones show planning, pollen shows handling, and block counts hint at quotas. The mystery holes likely tied market life to simple accounting, while the setting channeled traffic. Future work can test materials, date repairs, and model flows. Records may have lived in cords and ground together. This ridge still teaches how exchange and authority organize complexity.
