Research on Tianchi sediments in the Tianshan Mountains shows that warfare, rather than natural factors, was the main driver of the increased incidence of fires along the Silk Road over the past two thousand years. Human activities, such as intentional burning, agriculture, livestock farming, and metallurgy, all influence the frequency of fires in ecosystems. Dong Guanghui, Zhou Aifeng and colleagues studied whether another typical human activity affected the fire history of areas along the Silk Road: war.
War has played an important role in fire mechanisms; however, whether and when war influenced the history of fire along the Silk Road remains unclear. Using high-resolution records of black carbon in mountain lake sediments and war data from historical documents, researchers explored the relationship between fire, fuels, climate and human activity along the eastern stretch of the Silk Road over the past 6,000 years.
Fire was an important weapon in ancient Chinese warfare. Sun Tzu, the famous 5th century BC military strategist and author of "The Art of War," recommended using fire to deal with enemies. This historical context provides context for the findings.
The team measured black carbon, soot and coke in Tianchi Lake core sediments, which represent 6,000 years of sediment deposition. The authors calculated the land spatial extent of fire-related particulate matter in sediments using potential source contribution function analysis, a method commonly used to identify source areas of contemporary pollution.
Fires were infrequent during the mid-Holocene, but became more frequent during the late Holocene as the climate became drier and flammable herbaceous vegetation spread. Then, before 2000, fire frequency decoupled from climate or vegetation.
On a hundred-year time scale, fires and wars in this period were synchronized, and there are relevant records in the "List of Wars in Chinese History". The authors say that wars between different political forces, starting 2000-400 years ago, may have been the main cause of high-intensity fires in the region.
The results show that fire activity was less in the mid-Holocene but gradually increased in the late Holocene, a pattern closely associated with increased drought and expansion of herbaceous vegetation. However, over the past 2,000 years, the intensity and scale of ancient fires have increased significantly, and this pattern is no longer synchronized with climate and vegetation changes on centennial timescales; instead, the sequence is significantly positively correlated with the number of recorded wars across different dynasties. The study found that on a hundred-year time scale, wars between different political forces may have been the main influencing factor in the five high-intensity fires that occurred in the eastern section of the Silk Road since 2000 BC. This study reveals the impact of war activities related to dynastic changes on the fire system in Chinese history, providing a new perspective for understanding the impact of human activities on the environment.
References: Zhang Shanjia, Liu Hao, Li Gang, Zhang Zhiping, Chen Xintong, Shi Zhilin, Zhou Aifeng, Dong Guanghui: "Fires in the Eastern Silk Road Region Since 2000 BC War Impacts Exceed Climate Control", December 19, 2023, PNASNexus.
DOI:10.1093/pnasnexus/pgad408
Compiled source: ScitechDaily