Nearly 4,000 years ago, a landslide sent boulders and sediment tumbling into a valley of the Yellow River. The carnage created a massive earthen dam some 660 feet (200 meters) tall, cutting off the river for months.

When that dam finally burst and the river broke free, a massive flood raged across the countryside—and potentially altered the course of Chinese history.

That’s the story told by sediments and archaeological remains described Thursday in a provocative new study published in Science. If correct, the geologic evidence provides a kernel of truth to one of the country’s most important legends: a great flood that paved the way for the Xia, China’s semi-mythical first dynasty.

“Its importance is just like the story of Noah’s flood