But what wiped out this highly developed culture that blossomed 5,300 years ago has long puzzled scientists, who have suggested it could have been a result of flooding, freezing temperatures, military conflict or changes in the social structure.

Liangzhu is located in a low-lying region where flooding would have occurred in June, followed by a dry and hot July and August. The society had effectively managed water resources by building large dams to mitigate floods and irrigation to survive in a dry climate, according to the researchers, led by the Institute of Global Environmental Change at Xian Jiaotong University.

However, around 4,400 years ago they stopped building dams, the scientists wrote in a paper published in the journal Science Advances on Thursday. They said that was probably because of a megadrought that led people to believe the existing dams were sufficient for the climate, which turned out to be the driest period in Liangzhu’s history.

To reveal what caused the civilisation to abruptly collapse, the geologists and climate researchers looked for clues hidden in stalagmites in two caves called Shennong and Jiulong, 350km (217 miles) southwest of the central area of the Neolithic sites in Zhejiang province, in an area affected by the Southeast Asian monsoon.

The well-preserved rocks that grew on the cave floor from ceiling drippings are important climate archives that could help scientists reconstruct climatic conditions above the caves up to several 100,000 years into the past, according to the researchers.

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Lead author Zhang Haiwei, an associate professor with the Xian university institute, said Liangzhu people had experienced humidity never seen before after living in an arid climate for some 100 years.

“The extremely dry climate shifted suddenly to the other extreme of wetness, which had a devastating impact on the Liangzhu people’s living environment,” he said. “They relied on rice farming for food and the dryness might have led them to move to lower-lying land. Later, unexpected floods destroyed their farmlands and city.”

The team presented precisely dated speleothem records from the cave, which showed a period of extremely high rainfall between 4,345 and 4,324 years ago. Severe flooding of the Yangtze River hit the city hard, destroyed water infrastructure, wrecked the rice cultivation and forced people to leave.

The extreme humidity continued intermittently for another 300 years, keeping the low-lying land swamped and the sea level high, Zhang said.

“We suggest that massive flooding and inundation due to poor drainage in the low-lying land may have forced the Liangzhu people to abandon their capital city and dwellings in the Taihu Plain, ultimately leading to the collapse of the entire Liangzhu civilisation,” according to the paper.

Zhang said both the ancient floods and modern-day large destructive floods in the Yangtze region in 1954, 1998 and 2016 were largely linked to wetter conditions brought by El Nino, an abnormal warming of waters in the equatorial Pacific.

After Liangzhu collapsed, the Qianshanyang and Guangfulin cultures emerged, but they were technologically less advanced and battled wet conditions before they were brought down by a megadrought, according to the paper.

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There was a cultural gap for the next thousand years in the Yangtze River Delta, until the beginning of the Shang and Zhou dynasties (c1600-1050BC, and c1046-256BC). “The megadrought around 4,000 years ago and the ensuing unstable climate until 3,000 years ago might have brought this chapter of the Neolithic culture to the end in the Yangtze River Delta,” the paper said.