Literal demise around 4,300 years ago: A climate change that intensified the monsoon rains led to the collapse of the mysterious Liangzhu high culture in today’s China. This emerges from the analysis of deposits in stalactites in a cave in the region.
Monumental water infrastructures as early as the late Neolithic: In the Yangtze Delta, about 160 kilometers southwest of Shanghai, archaeological investigations have uncovered traces of an astonishingly early advanced civilization. The city of Liangzhu, which was characterized by a complex system of navigable canals, dams and water reservoirs, developed there from around 5300 years ago. This has also earned it the name “China’s Stone Age Venice”. Due to its cultural and historical importance, the archaeological site was finally declared a UNESCO World Heritage Site in 2019.
As the archaeological findings show, not only the Liangzhu City but also its surrounding area was criss-crossed by water infrastructures, which made it possible to cultivate very large usable areas all year round. The high level of this culture based on ingenious water management is also proven by the artfully crafted finds of grave goods made of jade. Metals, however, were still unknown. The Liangzhu culture also achieved a considerable continuity – but after around 1000 years of history it came to an abrupt end: around 4,300 years ago the monumental settlement structures were abandoned – why has remained unclear until now.
Searching for traces in stalactites
The archaeologists have not yet found any evidence of armed conflicts, but there have already been indications of another possible cause of the collapse: “A thin layer of clay was detected on the remains that had been preserved, suggesting a possible connection between the decline of the civilization and the floods of the Yangtze from the East China Sea, ”says Christoph Spötl from the University of Innsbruck. “However, no clear conclusions could be drawn about the cause from the mud layer itself,” explains the geologist. So Spötl and his international colleagues went looking for further clues. In doing so, they turned to a special source of information: stalactites.
As the researchers explain, these structures in caves can be used as climate archives to reconstruct the climatic conditions in the past. The method is based on the fact that dripstones are built up from layers that were applied by water that comes from precipitation on the surface. The locations can be dated through characteristics of certain isotope values and conclusions can also be drawn about the amount of rain.
The scientists identified two systems southwest of the excavation site as suitable caves for studying the history of the development of rainfall in the Liangzhu region: Shennong and Jiulong. “These caves have been well explored for years. They are in the same area of influence of the Southeast Asian monsoon as the Yangtze Delta and with their stalactites allow us an exact look into the time of the collapse of the Liangzhu culture, which, according to archaeological findings, happened around 4,300 years ago, ”says Spötl. The scientists obtained samples of stalagmites in both caves for laboratory analyzes.
Intensified monsoons at the time of the downfall
As they report, the results of the examination of the stalactite layers actually showed an unusually humid climatic phase in the history of the region. Dating using the uranium-thorium method showed: The very strong monsoon rains struck the area between 4345 and 4324 years ago. This wet period therefore fitted in perfectly with the assessments of the demise of the Liangzhu culture. The scientists emphasize that the measurement accuracy is only around ± 30 years. “In view of the time dimension, this is astonishingly precise,” says Spötl.
According to the researchers, it is obvious what the heavy rainfall meant for the Liangzhu culture, which is based on water management: “The massive monsoon rains are likely to have flooded the Yangtze and its tributaries so severely that even the highly developed dams and canals no longer hold these water masses withstood and destroyed Liangzhu City, ”says Spötl. Apparently the people fled from the floods and did not return to the place later. In other words: It is now clear that a climatic-historical development with a wet result sealed the fate of Venice in the Stone Age.
Source: University of Innsbruck, specialist article: Science Advaces, doi: 10.1126 / sciadv.abi9275