The Tibetan Plateau is one of the highest inhabited regions in the world, and while life at the so-called “Roof of the World” may be harsh, new data shows that the area has enjoyed a warmer spell , which gave rise to the mighty Tibetan Empire. . However, despite exerting a huge influence on the geopolitics of Asia between the seventh and ninth centuries CE, the empire collapsed over a period of about 60 years, as colder temperatures and drought led to a catastrophic decline in resources agriculture throughout the region.
To learn more about the impact of climate change on the rise and fall of the Tibetan Empire, the authors of a new study analyzed carbonates and oxygen isotopes in sediment layers collected from Lake Jiang Co on the central Tibetan plateau. Combining this with biomarkers left behind by ancient algae, they were able to reconstruct the temperature and precipitation record of the last 2,000 years.
In doing so, the researchers found that summer temperatures between 600 and 800 CE were about 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 period coincided with an increase in rainfall, making the region more suitable for both agriculture and animal husbandry.
“The unique hot and humid climate at 600-800 [CE] corresponds closely to the most prosperous period of the Tibetan Empire,” the authors of the study wrote. During this period, they estimate that the arable land area for barley cultivation would increase by 24.48 percent.
“The expansion of agriculture, animal husbandry, and the accumulation of surplus resources may have been preconditions for social class stratification and the emergence of royal power, allowing the expansion of the Tibetan Empire across the Plateau and surrounding areas,” a the researchers explained.
Correlating their climate data with historical sources, the study’s authors show how the empire tended to invade neighboring territories during very hot, wet years, while enemies typically launched counter-raids in cooler weather. and drier. “This suggests that the Tibetans took advantage of resources obtained from animal husbandry and farming to equip these military incursions during wet years,” they explain.
The rulers of the Tibetan Empire tended to seek truces and alliances with other superpowers when resources were low, indicating their need to adopt strategies to mitigate the negative effects of climate change.
During its 200-year existence, the empire conquered parts of Xinjiang and Kashmir, as well as capturing a stretch of the fabled Silk Road. After reaching its peak around 800 CE, however, the nomadic realm suddenly declined as conditions on the Tibetan Plateau rapidly deteriorated.
“From the late 8th century to the middle of the 9th century, precipitation decreased significantly, and a severe drought prevailed for about 60 years,” the researchers wrote. “The peak of the drought was around 840 [CE] coincided with the fall 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 reduction in agricultural resources may have led to more wars among different tribes, as well as religious conflicts, and finally accelerated the fragmentation of the empire in regional policies after years of drought prevailing,” the authors conclude.
The study is published in the journal Science Bulletin.