Thousands of regularly arranged hollows run across a hillside in Peru’s Pisco Valley. Monte Sierpe, often called the Band of Holes, is an archaeological mystery about human activity: what were these excavations for, and how did their arrangement work?
A research article first published online in November 2025 offers an exchange-and-accounting interpretation. That is a testable proposal about a surviving place, rather than evidence for the extraordinary origins sometimes attached to unusual ancient monuments.
What is actually there?
The University of Sydney’s account describes a band roughly 1.5 kilometres long, containing around 5,200 depressions arranged in sections. It explains that aerial photographs brought the feature wider attention in 1933 and that its purpose has been debated.
The same institutional report connects the site with a landscape where highland and coastal communities could meet. It presents a possible sequence: an exchange place under the Chincha, later incorporated into Inca administration. These are the researchers’ interpretations, not labels found written beside the holes.
The study and the dates
Jacob L. Bongers and colleagues combined aerial mapping with sediment analysis. The open-access Antiquity paper reports sampling 19 holes and two locations outside the band, numerical regularities in the layout, and plant microremains. Charcoal from one hole produced a calibrated interval of AD 1320–1405 at 95.4% probability.
That date concerns one sample. It is not a construction date for every depression. The paper also discusses the monument within broader pre-Hispanic periods, proposing earlier use and continuation into Inca times.
The University announcement is dated 10 November 2025; the journal assigns the article to its February 2026 issue. Neither date describes a new event in 2026. UKPX therefore does not count this entry towards a current-year incident target.
Why an arrangement might function as a record
A repeated layout can organise activity without containing writing in the familiar sense. Separate spaces can distinguish groups of goods, tasks or obligations. A useful interpretation must nevertheless show why a particular arrangement supports one kind of activity better than another.
The paper compares the layout with knotted-string records, or khipus, including an example from the Pisco area. The comparison suggests an accounting possibility; it does not supply a translation of the hillside into a recovered ledger. UKPX does not assign a crop, quantity or taxpayer to a particular row.
This is the difference between recognising structure and decoding its meaning. An intentional pattern may be clear while its administrative purpose remains uncertain. A resemblance becomes more informative when supported by context and independent material evidence, rather than being treated as an explanation on its own.
Plants in the holes
The Sydney announcement highlights maize and reed evidence and suggests that goods may have arrived in woven containers or bundles. It presents a marketplace as a hypothesis supported by several kinds of evidence, while explicitly acknowledging unanswered questions.
Plant traces are valuable because they let researchers investigate use rather than infer everything from appearance. Their interpretation still depends on how material entered a sample and whether it belongs to the activity being reconstructed. A plant remain and a proposed market transaction are different levels of inference.
The presence of goods would not automatically distinguish temporary sorting, exchange and longer storage. Establishing duration, repeated use and differences between sections would make the alternatives easier to compare. These are questions prompted by the research, not additional results claimed by UKPX.
What the proposal does not settle
The open paper treats the function as uncertain and advances an Indigenous explanation grounded in organisation and material evidence. Its conclusions should not be compressed into a claim that every hole has been explained.
Nor does uncertainty about a function establish an extraordinary builder. “We do not yet know exactly how this system worked” is not evidence that people lacked the capacity to create it. The interesting problem is the form of social organisation that could make the arrangement useful.
A strong follow-up would test whether patterns recur across independently defined sections, obtain additional secure dates and compare material from more holes and controls. Such work could strengthen the current interpretation, reveal different uses over time or favour another explanation. No outcome is assumed here.
Location, photographs and access
The broad map reference identifies the Band of Holes at Monte Sierpe. It is not the position of an individual sample, and it should not be used as a visitor entrance. Current unrestricted public access has not been verified for this entry, so it is not designated as a public place to visit.
The lead image is Figure 3 from the research article: photographs by J. L. Bongers and C. Stanish, reused with attribution under the paper’s CC BY 4.0 licence. These show the real archaeological feature. They are not an illustration of a reconstructed transaction.
Sources and further reading
Bongers et al., “Indigenous accounting and exchange at Monte Sierpe (‘Band of Holes’) in the Pisco Valley, Peru”, Antiquity — open research article; methods, results, discussion and photograph credit examined.
University of Sydney announcement, 10 November 2025 — the researchers’ explanation for a general audience. It reports the same study and is not an independent replication.
Band of Holes geographical reference — coordinate anchor only, checked against the named site in the primary research. Sources checked 11 November 2026.