(TibetanReview.net, Jul19’23) – Climate changes played a role in the rise and fall of the Tibetan empire in the earlier part of the medieval period, according to scientists from the Chinese Academy of Sciences Jul 17. The warm and humid climate during the 7th-9th centuries AD and the subsequent cold and aridification are consistent with the rise and fall of the Tibetan Empire, they have said.
Climate change is one of the possible reasons for the rise and fall of the Tibetan Empire, scientists from a unit of the academy’s Institute of Tibetan Plateau Research have said in a peer-reviewed report cited in a press statement posted on eurekalert.org Jul 17.
The research team was stated to have obtained a high-resolution climate record of the past 2000 years using the varved sediments of Jiang Co lake, located just north of Tibet’s capital Lhasa, on the central Tibetan Plateau.
In doing so, the researchers discovered that summer temperatures between 600 and 800 AD were around 2°C (3.6°F) warmer than in previous and subsequent cool periods. Meanwhile, changes in the depth and size of the lake indicate that this warm spell coincided with an increase in rainfall, all of which would have made the region more suitable for both agriculture and animal husbandry.
This meant that the 7th-9th centuries AD was an unusually warm and humid period.
Comparing this period with historical literature, the researchers have reported having found that it coincided with the appearance of the only unified local regime, the Tibetan Empire, on the Tibetan Plateau at that time.
The Chinese scientists have reported having found that changes in warm and humid climate and cold and dry climate were highly correlated with the foreign policy changes of the Tibetan Empire during that period. Combined with the ecological niche model, the researchers simulated the area of highland barley cultivation during the warm and humid period of the 7th-9th centuries AD and the subsequent cold and dry period, which differed by about 10.88 million hectares.
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The rulers of the Tibetan Empire also tended to seek out truces and alliances with other superpowers when resources were low, illustrating their need to adopt strategies to mitigate the negative effects of climate change, iflscience.com Jul 18 cited the study as saying.
During its 200-year existence, the empire conquered parts of Xinjiang and Kashmir, as well as seizing a stretch of the fabled Silk Road. However, after reaching its peak around 800 AD, the realm took a sudden nosedive as conditions on the Tibetan Plateau rapidly deteriorated.
“From the end of the 8th century to the mid 9th century, precipitation decreased significantly, and severe drought prevailed for about 60 years,” the researchers have written. “The peak of the drought at approximately 840 [AD] coincided with the collapse of the Tibetan Empire.”
During this period, the area of land available for barley cultivation decreased by 10.88 million hectares (26.89 million acres). “This decline in agricultural resources, in addition to religious conflicts, may have resulted in more wars among different tribes, and finally accelerated the Empire fragmentation into regional polities after decades of prevailing drought,” the authors have written.
The study is published in the journal Science Bulletin.