Ancient Wall Peru El Niño. Image credit: Gabriel Prieto/Huanchaco Archaeological Project

Ancient Wall in Peru Was Used to Protect Against Floods 1,000 Years Ago

More than one thousand years ago, ancient people built a 10-kilometer-long wall to protect against El Niño-induced flooding.


Recent studies reveal that an ancient Peruvian wall was constructed 1,000 years ago to guard against El Niño floods, challenging prior theories. New research suggests that a 1,000-year-old wall in the Peruvian desert, known as Muralla La Cumbre, was constructed to safeguard fertile farmlands and irrigation canals from El Niño-induced flooding.

Characterized by unusually warm ocean temperatures in the Equatorial Pacific, El Niño typically occurs every two to seven years and lasts for about a year. The phenomenon has profound impacts on global weather, often leading to increased rainfall in South America, drought in the Western Pacific, and shifting hurricane patterns in the Atlantic. While El Niño can provide certain benefits, such as replenishing water supplies in dry regions, it often leads to severe flooding, devastating droughts, and other natural disasters.

Archaeologists previously speculated that the Chimú people, who resided near Trujillo, constructed the 10-kilometer-long wall to defend their land from Incan invasions. However, the latest findings support the hypothesis that the wall was erected as a flood barrier during the region’s rainy periods.

An Ancient Wall in Peru to Protect Against El Niño

El Niño, a climate cycle that brings significant rainfall to the region around Christmas every few years, causes severe floods in Ecuador and northern Peru, while inducing drought elsewhere. “El Niño floods have been a threat to the Chimú for thousands of years,” said Gabriel Prieto, an archaeologist at the University of Florida.


The Chimú, who rose to prominence around 900 AD, were renowned for their unique pottery and metalwork, as well as the ruins of their capital, Chan Chan, a UN World Heritage Site. The Chimú’s moon-worshiping culture remained independent until their conquest by the Incas around 1470, just decades before the Spanish arrived in South America.

Findings Supporting the Flood Defence Theory

Upon examination, Prieto found layers of flood sediment on the eastern side of the 2.5-meter high La Cumbre wall. This suggests that it was built to shield Chimú farmlands on the coast to the west. Radiocarbon dating indicates that the wall’s construction started around 1100 AD, possibly in response to a major El Niño flood.

The wall, erected on two dry riverbeds prone to El Niño flooding, functioned like a dam, protecting farmland and Chan Chan, which was connected by canals. Prieto’s earlier discoveries of mass child sacrifices at Chimú sites suggest a possible link between these sacrifices and the recurring El Niño floods.


Expert Opinions and Further Insights

Edward Swenson, an archaeologist at the University of Toronto, commended Prieto’s research while proposing that the wall may also have served a defensive purpose. He said, “I believe it was some sort of political game.” However, the ancient wall’s precise purpose and the societal impacts of El Niño floods on the Chimú warrant further investigation.

PLEASE READ: Have something to add? Visit Curiosmos on Facebook. Join the discussion in our mobile Telegram group. Also, follow us on Google News. Interesting in history, mysteries, and more? Visit Ancient Library’s Telegram group and become part of an exclusive group.

Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

Write for us

We’re always looking for new guest authors and we welcome individual bloggers to contribute high-quality guest posts.

Get In Touch