China’s mythical ‘Great Flood’ possibly rooted in real disaster

Ancient Chinese tales and writings about a massive flood of the Yellow River that led to civilization’s rise in East Asia appear to hold water, researchers say.

A section of the Yellow River dammed by an earthquake-caused landslide broke open about 3,936 years ago, says a team led by geologist Qinglong Wu of China’s Nanjing Normal University. A wall of water about one-third as high as the Empire State Building charged down the Yellow River valley, possibly changing the river’s course and leading to years of flooding in lowland areas inhabited by farmers, the scientists report in the Aug. 5 Science.

“This was one of the largest known floods on Earth over the past 10,000 years,” geologist and study coauthor Darryl Granger of Purdue University in West Lafayette, Ind., said at a news conference.

That natural disaster came to be known as the Great Flood, first in Chinese folktales and later in written histories from around 3,000 years ago, the researchers propose. These accounts tell of a hero named Yu who spent decades leading efforts to dredge rivers and drain floodwaters, as well as personally fighting off supernatural beasts, following catastrophic flooding of the Yellow River. Legend has it that Yu’s success enabled him to launch Chinese civilization by founding the Xia dynasty.

Some scholars regard this tale as a myth or as propaganda devised to justify centralized, imperial rule.

Historical records of the Xia dynasty are scanty, archaeologist and study coauthor David Cohen of National Taiwan University in Taipei said at the news conference. New evidence of an ancient Yellow River flood “provides a tantalizing hint that the Xia dynasty actually existed,” Cohen said.

Wu’s team studied remains of a landslide dam along the Yellow River in north central China. Remnants of the dam, found on the left and right riverbanks, included masses of soil and shattered rock typical of landslides. A scar in the earth above the right bank must have been created by the landslide, the researchers say. The ancient dam backed up a lake that was about 200 meters deep, they estimate.

Downstream, the team found sediment and boulders carried by floodwaters. Flood sediment covered the remains of a previously excavated human settlement called Lajia, located 25 kilometers below the ancient dam. Cracks in the ground and flattened structures suggest an earthquake destroyed Lajia and killed its residents before the flood. The same earthquake probably triggered the landslide upstream that blocked off the Yellow River for roughly six to nine months before the natural dam burst, Wu’s team says.

Radiocarbon dating of human bones and burned bits of wood from Lajia yielded an approximate age for the flood.

Great floods and other natural disasters have long played central roles in folktales and oral histories around the world. Scientists disagree about whether geological evidence of past deluges shows that flood stories told over hundreds of generations describe actual events (SN Online: 9/22/15).

But the flood evidence uncovered by Wu’s team shows that Emperor Yu’s flood is “potentially rooted in geological events,” geologist David Montgomery of the University of Washington in Seattle writes in the same issue of Science. “A telling aspect of the story — that it took Yu and his followers decades to control the floodwaters — makes sense in light of the geological evidence.”

Despite the new findings, “nothing is certain” about how the ancient Chinese state formed, says historian David Keightley of the University of California, Berkeley, who studies the origins of Chinese civilization.

If the newly documented Yellow River flood became known as the Great Flood, China’s Xia dynasty must have started around 3,900 years ago, Wu’s group speculates. That’s about 170 to 300 years later than investigators had previously estimated.

But the timing of the flood does roughly match up with the first appearance of China’s Bronze Age urban societies, including the Erlitou culture of the Yellow River valley. Previously excavated Erlitou bronze vessels and other artifacts are remnants of the Xia dynasty, the researchers suspect.