Conny Waters – AncientPages.com – Approximately 4,600 years ago, the Shijiahe civilization flourished in China’s Middle Yangtze River region. This society was notable for its advanced culture, featuring palaces, city walls, sophisticated water management systems, and thriving jade and pottery industries.
Background: A view of the Yangtze River, China. Credit: Wikipedia – CC0 1.0 – Front: Jade ornament with face and masks, Shijiahe culture. Credit: Smithsonian Museum – CC BY-SA 4.0 – Image compilation AncientPages.com
However, within a millennium, the Shijiahe culture collapsed and its people migrated out of the area. The reasons behind this sudden decline have long been debated—some suggested invasion by raiders from the Central Plains while others pointed to significant climate changes.
Recent research led by scientists from Oxford’s Department of Earth Sciences has provided new insights into this historical mystery. The team analyzed a stalagmite from Heshang Cave in the middle Yangtze Valley to reconstruct a detailed record of past rainfall patterns. Stalagmites form as rainwater drips from cave ceilings; minerals dissolved in the water deposit layers of calcium carbonate that gradually build up these formations.
By conducting high-precision chemical analyses on these layers—totaling 925 individual measurements—the researchers were able to accurately date each layer and estimate annual rainfall amounts over a thousand-year period. This “rainfall yearbook” offers valuable evidence about environmental conditions during the rise and fall of the Shijiahe civilization.
Heshang Cave, in the middle of the Yangtze River valley. Credit: University of Oxford
The reconstruction of the valley’s climate history identified three prolonged periods of low rainfall—each receiving less than 700 mm annually and lasting between 40 and 150 years—and two intervals of high rainfall, with over 1,000 mm per year, which persisted for approximately 80 and 140 years. When these findings were compared with archaeological records from the region, researchers observed that the wetter periods corresponded with increased flooding events, widespread expansion of wetlands, and a notable decline in population within the valley.
A particularly significant shift occurred around 3,950 years ago. This marked the onset of the longest high-rainfall interval detected by researchers. During this time, excessive precipitation led to expanding lakes throughout the Middle Yangtze valley and caused extensive waterlogging in low-lying areas.
As a result, land suitable for settlement and agriculture became scarce. This environmental transformation had a profound effect on local societies such as the Shijiahe culture; archaeological evidence shows a sharp decrease in remains from this period onward—a sign that population numbers fell dramatically and remained low for centuries.
Further evidence indicates that after this decline, people abandoned urban centers within the valley itself and relocated to higher ground in surrounding regions.
The work builds on Oxford’s ‘Environmental Proxies’ and ‘Climotope’ groups, known for pioneering quantitative reconstructions of past environments. This includes ongoing research into new geochemical techniques and mass-spectrometry approaches. Notably, these groups first used calcium isotope measurements in cave stalagmites to reconstruct annual rainfall in easily understood units (mm per year).
“It is fabulous to see this 1000-year record of rainfall-amount now available to the scientific community. Such robust data sets are fundamental for understanding the functioning of our environmental systems in times of rapid change. They also enable close collaboration with a multitude of University of Oxford research teams working to tackle environmental challenges (e.g. environmental scientists, archaeologists, climate modellers),” corresponding author Dr Christopher Day (Department of Earth Sciences) said in a press release.
The new study is a result of ongoing collaboration between Oxford and the China University of Geosciences, Wuhan. Lead author Dr. Jin Liao visited Oxford to use their specialist milling equipment to sample a stalagmite at high resolution. Oxford-developed isotope tools were then used to accurately date the sample and reconstruct past rainfall.
The HS4 stalagmite which was used to create the ‘rainfall yearbook’. Credit: University of Oxford
“We’ve worked with our Chinese colleagues to understand Chinese climate change for many years, but only recently extended this work to assess how past societies in central China were impacted by changes in monsoon rainfall. The data, and the knowledge Jin brought about the Shijiahe culture, enabled us to demonstrate, for one of the first times, that high rain can cause problems for past societies, as well as drought conditions,”co-author Professor Gideon Henderson (Department of Earth Sciences) said.
Researchers have found that their analysis provides important insights for managing both current and future environmental changes. The study shows that the highest annual rainfall during the collapse of the Shijiahe civilization was 1200 mm per year, which is lower than the peak yearly rainfall of 1500 mm recorded in the past 120 years. While advances in water-management have allowed this region to become a major rice-producing area in China, rising temperatures linked to climate change are expected to intensify extreme flooding events, posing increased risks to local communities.
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“This not only reflects the limited adaptive capacity of ancient societies, but also highlights the critical importance of modern-day water management infrastructure, agricultural innovations, and governance systems in mitigating climate risks and safeguarding food security. Effectively managing these climate-driven extremes will thus become an essential challenge for achieving sustainable societal development in a climate-changing world,” Dr. Jin Liao (China University of Geosciences, Wuhan), lead author of the study, said.
The study was published in the journal National Science Review.
Written by Conny Waters – AncientPages.com Staff Writer