Ancient Chinese legend tells of a cataclysmic event that happened 4,000 years ago, a story that might sound familiar to those acquainted with the biblical story of Noah's flood.

As the tale is told, ancient China was left in watery ruins after a great flood, flowing from the Yellow River, or the Huáng Hé, devastated the landscape. But from this apocalyptic event arose a hero, Yu, who was able to rebuild the country. Yu later went on to found the legendary Xia dynasty, the first dynasty in Chinese history.

Due to scant archaeological evidence, many modern scholars dismiss this legend as mere myth, a fantastical origin story that has been passed down orally through history but which has no basis in fact, much like the Noah story in the Bible. But where archaeologists are left wanting, a shocking new discovery by geologists is making scholars take a second look at the legend: evidence of a catastrophic flood that poured through the Yellow River valley some 4,000 years ago, reports National Geographic.

Qinglong Wu of China’s Peking University is the lead author on the new study. He first found hints of an ancient flood back in 2007 when he noticed yellowish deposits in the Jishi Gorge, an upstream river valley for the Yellow River. The deposits found throughout the gorge indicated the existence of an ancient lake, as if the river had been dammed at one point.

Wu then examined ancient cave dwellings just 16 miles downstream from the Jishi Gorge site, which is known to have been destroyed by an ancient earthquake. Radiocarbon dating of human bones at this site date the destruction to about 3,900 years ago. Furthermore, analysis of sediments found near this site were discovered to have come from Jishi Gorge.

Then later still, Wu found the missing puzzle piece: evidence of a mammoth earthen dam in the Jishi Gorge, a dam that once would have been some 660 feet tall.

“That’s as big as the Hoover Dam or the Three Gorges Dam,” said Purdue University geologist Darryl Granger, one of the study’s co-authors. “Imagine a dam like that failing."

The team surmised that a sequence of dire events began with an earthquake nearly 4,000 years ago that started a landslide in the gorge, which then blocked the river and created a huge lake. As the water built up, the dam eventually broke, releasing nine months’ worth of river water in a matter of hours. Floodwaters reached heights of up to 131 feet above the river’s normal banks, and the great deluge would have filled the lowlands hundreds of miles away. Watery conditions could have lasted for years and transformed the Chinese landscape.

Wu thinks that the geological evidence should lend credence to the legend of the Xia.

“The Xia, the great flood, and the control of it have been taken as truth for more than 2,500 years in China," he said. "Now, we have provided the scientific evidence for the flood — [which] means that other texts about the Xia dynasty should be reliable.”

Of course, scholars are still likely to debate the depth of the legend for many years to come, but this is the first time real physical evidence has been found that directly corroborates it. It makes you wonder what other great legends considered myth today might also be true.