Sediment analysis and drone photography of the iconic South American monument of Monte Sierpe (aka “Band of Holes”) support a new interpretation of this mysterious landscape feature as part of an Indigenous system of accounting and exchange.

Stretching 1.5 km across the Pisco Valley of the southern Peruvian Andes, Monte Sierpe (meaning serpent mountain) is a large row of approximately 5,200 precisely aligned holes (1–2 m wide and 0.5–1 m deep), organized into sections or blocks.

It first gained modern attention in 1933, when aerial photographs of the holes were published in National Geographic, but the monument’s purpose is still uncertain.