The famous Andean monument may have been used to hold indigenous people accountable

Sediment analysis and drone photography of South America’s famous Monte Serpi Monument (also known as the “Band of Holes”) supports a new interpretation of this enigmatic landscape feature as part of an indigenous accounting and exchange system.

Stretching 1.5 km across the Pisco Valley in the southern Andes of Peru, Monte Serpe (i.e. Serpent Mountain) is a large row of approximately 5,200 precisely aligned craters (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 in National GeographicBut the purpose of the memorial remains uncertain.

“Hypotheses regarding the purpose of Monte Serpi range from defence, storage and accounting to water collection, fog capture and horticulture,” says lead author Dr Jacob Bongers from the University of Sydney. “The function of the site is still unclear.”

To shed new light on this enigmatic feature of the ancient Peruvian landscape, an international team combined microphytogenetic analysis of sediment samples from the holes with high-resolution aerial photographs, providing new insights into the organization and use of Monte Serpe at both micro and macro scales. Their results are published In the magazine Antiquity.

According to the authors, the most significant of their findings was microbotanical evidence, which revealed plant remains in the holes, including crops such as corn and wild plants traditionally used to make baskets.

“These data support the hypothesis that during pre-Hispanic times, local groups periodically lined the holes with plant material and deposited goods within them, using baskets and/or woven bundles for transport,” explains Dr Bongers.

Perhaps most interesting are the aerial photographs, which indicate digital patterns in the layout of the holes. Besides the fragmented organization of the monument, Monte Serpi reflects the quipu: Inca counting devices made of knotted chain.

This may indicate that Monte Serpi constituted a massive accounting system during the Inca period, and was administered by the Inca state to collect tribute.

Most importantly, Monte Serpi is strategically located between two Inca administrative sites and near the intersection of a network of pre-Hispanic roads. It is located in a transitional ecological zone (chaupiyunga) between the highlands and the lower coastal plain, an area where groups from both regions meet and exchange goods.

Together with the microflora and meteorological findings, this indicates that Monte Cerbe was initially built and used by the pre-Inca kingdom of Chincha for organized barter and exchange, later developing into a place of accounting under the Inca.

“This study contributes an important Andean case study of how past societies modified past landscapes to bring people together and enhance interaction,” Dr. Bongers concludes. “Our findings expand our understanding of barter markets and the origins and diversity of indigenous accounting practices within and beyond the ancient Andes.”