Drone Mapping and Seed Evidence Reinterpret Peru’s 'Band of Holes' as Pre-Inca Market and Inca Record Site

Archaeologists Charles Stanish and Dr. Jacob Bongers have new evidence that sheds light on one of Peru’s most enduring landscape mysteries: the so‑called Band of Holes on Monte Sierpe in the Pisco Valley. The feature—more than 5,200 shallow pits carved into the hillside—has provoked decades of speculation about its origin and function.

On recent expeditions the team used high-resolution drone mapping to produce the first complete aerial survey of the site. The imagery reveals striking, segmented rows of pits—each roughly 3 to 6.5 feet wide—arranged in a mathematically suggestive pattern. Stanish and Bongers liken the layout to khipus, the knotted-string recording devices used by the Inca for counting and administration.

Complementing the aerial work, microbotanical analysis of sediment from inside multiple pits turned up fossilized seeds of maize and wild plants, plus reed and willow fibers historically used by Andean peoples for bundling and transporting goods. The researchers argue these remains point to deliberate human placement rather than accidental deposition.

"We proved that the seeds didn’t fly in, they weren’t airborne, they had to be put there by humans," Stanish said. He noted that most samples are consistent with pre‑Inca activity and that at least one carbon date places material slightly before the Inca period; a single colonial‑era seed was recovered from deep within one pit.

Taken together, the aerial patterns and botanical evidence support an interpretation in which the pits originally served as a rudimentary pre‑Inca marketplace or storage layout that the Inca later adapted into an administrative or accounting system tied to agricultural production. The khipu‑like organization would have enabled systematic counting and management of commodities.

Stanish said further laboratory work is under way to examine recovered seed assemblages in greater detail, and Bongers is planning follow-up excavations to test the hypothesis more thoroughly. Both researchers acknowledge that new finds could refine or revise their interpretation, but they expressed confidence in the current evidence.

The team also urged Peruvian authorities and local communities to protect Monte Sierpe from development and agricultural alteration. "People have to make a living, and I admire that," Stanish added, "but this is a precious site for Indigenous peoples and for their cultural heritage."

Key facts: Monte Sierpe contains more than 5,200 man‑made pits (3–6.5 ft wide); drone mapping reveals organized, segmented rows reminiscent of khipus; microbotanical samples include maize, reed and willow fibers; at least one sample dates slightly pre‑Inca, with one colonial seed found deep in a pit. Further excavation and analysis are planned.