Long-Lost River Discovered in the Himalayas May Completely Change What We Know About Early Civilizations

This long-dried-up river did not play as active a role in ancient human civilization as we once thought. MONEY SHARMA/AFP/Getty Images

Scientists once believed that a long-dried-up river in the Himalayas served as the main water source for the Indus Valley Civilization, also known as the Harappan Civilization, which existed from 5300 B.C. to 3300 B.C. in South Asia. Now, scientists have found the ancient remains of the river that prove it did not exist at the same time as the Indus. That means their civilization existed without a major active water source, something archaeologists did not believe was possible.

In a study now published online in Nature Communications, researchers from Imperial College London and the Indian Institute of Technology Kanpur found and dated the remains of an ancient river known as the Sutlej, which once flowed through the Himalayan area. Research revealed that the river dried up around 8,000 years ago, a full 3,000 years before the development of the Indus Valley Civilization. The finding showed that the urban area was able to grow and thrive for several thousand years despite not having an actively flowing river nearby.

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"The findings challenge our current understanding of how urbanization in many ancient civilizations began and grew in relation to natural resources," explained lead researcher Sanjeev Gupta, from the Department of Earth Science and Engineering at Imperial College London, Phys reported. "Contrary to current belief, it was the departure of a large river, rather than its arrival, that triggered the growth of Indus urban centers."

The team was able to find the now-extinct river by looking at the "scars" it left alongside the modern Ghaggar-Hakra River. The team drilled through the dry Ghaggar-Hakra riverbed and analyzed layers of river sediments to determine how old the sediments were. They did this by measuring how much energy in the form of radiation was still stored in the sediments. Since energy builds over time (as long as the minerals are not exposed to light), the readings offered a near-accurate description of how long the sediments had been buried.

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But how could a major civilization have survived without a water source? The team determined that the "scar" the dried-up Sutlej River left captured water flow during monsoons, which may have acted as a water source for settlements in the area, Phys reported.

The findings were significant, as they gave insight into how ancient civilizations rose and thrived. The previously accepted theory was that ancient civilizations needed an active water source nearby to thrive. Scientists thought that once a water source dried up, ancient people were forced to move on.

"We now know that, given the right conditions, valleys that have lost their rivers can still serve as a water source," said coauthor Rajiv Sinha, from the Indian Institute of Technology Kanpur, Phys reported.