CHINA’S leaders are immensely proud of their country’s ancient origins. President Xi Jinping peppers his speeches with references to China’s “5,000 years of history”. The problem is that archaeological evidence of a political entity in China going back that far is scant.
There is some, including engravings on animal bones, that shows the second dynasty, the Shang, really did control an area in the Yellow river basin about 3,500 years ago. But no such confirmation exists for the legendary first ruling house, the Xia. Even inside China, some historians have long suspected that the country’s founding story—in which Emperor Yu tames flooding on the Yellow river (with the help of a magic black-shelled turtle, pictured), earns for himself the “mandate of heaven” and establishes the first dynasty—was either a Noah’s-Ark flood-myth or perhaps propaganda invented later to justify centralised state power. This month, however, state-controlled media have been crowing over newly published evidence in Science, an American journal, that at least the flooding was real. This, they say, has made it more credible that the Xia was, too. Not everyone is so convinced.
Catastrophic floods leave their mark on soil and rocks. Qinglong Wu of Peking University and others have examined the geology of the upper reaches of the Yellow river. In the journal, they conclude that a vast flood did take place in the right area and not long after the right time for the supposed founding of the Xia. Although their evidence does not prove the existence of an Emperor Yu or of the dynasty he founded, it does provide a historical context in which someone might have gained power with the help of flood-taming exploits.
According to Mr Wu, a vast landslide, probably caused by an earthquake, blocked the course of the Yellow river as it flowed through the Jishi gorge on the edge of the Tibetan plateau. For six to nine months as much as 16 cubic kilometres (3.8 cubic miles) of water built up behind the accidental dam, which, when it finally burst, produced one of the biggest floods ever. At its peak, the authors calculate, the flow was 500 times the normal discharge at Jishi Gorge. Mr Wu reckons the ancient flood could easily have been felt 2,000km downstream in the area of the Yellow river said by Chinese historians to have been the realm of the Xia.
At about this time, either coincidentally or (more probably) because of the flood, the river changed its course, carving out its vast loop across the north China plain. The significance is that, while the river was finding its new course, it would have flooded repeatedly. This is consistent with old folk tales about Emperor Yu taming the river not through one dramatic action, but by decades of dredging.
The ancient flood can be dated because the earthquake that set the catastrophic events in motion also destroyed a settlement in the Jishi gorge. Radiocarbon dating of inhabitants’ bones puts the earthquake at about 1920BC—not 5,000 years ago but close-ish. Xinhua, a state news agency, lauded the study as “important support” for the Xia’s existence. Xu Hong of the Chinese Academy of Social Sciences challenged this, saying the scholars’ findings had not proved their conclusions. The first dynasty has gone from myth to controversy.