Around 4,000 years ago, a hero named Yu halted a massive flood and earned a divine mandate to create the Xia dynasty, China's first. Well, so the story goes. But like so much ancient history, it can be difficult to know where fiction ends and fact begins. Scientists have now discovered the first geological evidence that China's Great Flood did take place, shedding further light on how one of the world's oldest civilizations got its start.

Chinese legend has it that Emperor Yu made a name for himself by dredging the Yellow River, boosting its water capacity and therefore tempering the flood's catastrophic waters. This tale was passed down over 500 years before it was entered into historical records. But with no geological evidence to back up the story, scholars have questioned whether the Great Flood, and the Xia dynasty for that matter, actually took place.

An international team of scientists has now used carbon dating to uncover evidence of a huge earthquake-triggered landslide, significant enough to block the path of the Yellow River, the third largest river in Asia. This blockage apparently gave rise to an almighty dam, which eventually burst and flooded huge swathes of surrounding land with up to 300,000 to 500,000 cubic meters of water per second, making it one of the biggest floods the Earth has seen in the past 10,000 years.

The new information came from analysis of children's skeletons that had been crushed in the earthquake in the months leading up to flood. The researchers say the skeletons are particularly useful samples because children's bones grow so quickly that "their radiocarbon age is a true representation of the time that they died."

The dates of the children's death lined up with the dates of the youngest charcoal found in the flood sediment, which allowed the researchers to calculate the date of the flood at around 1,920 BCE. This shifts understanding of China's roots somewhat. The Xia dynasty is traditionally thought to have kicked off in 2,200 BCE according to some historians, or 2,070 BCE according to the Chinese government's Xia-Shang-Zhou Chronology Project.

"The date of the flood circa 1920 BCE, though, roughly marks the beginning of the Bronze Age in China," says study co-author, David Cohen. "A major transition occurred then, with the appearance of the first bronze ritual vessels and weapons, as well as walled settlements on a scale not seen in the Neolithic. These are the hallmarks of state-level societies in China, which come to appear across the landscape of the Yellow River valley."

The research was published in the journal Science and the video below offers an overview of the discovery.

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