A study of Tianchi Lake sediments shows that warfare, rather than natural factors, became the primary driver of increased fire occurrences along the Silk Road over the past 2,000 years.
Impact of War on Fire Frequency Along the Silk Road
Human activities such as intentional burning, agriculture, pastoralism, and metallurgy can affect the frequency of fire in an ecosystem. Guanghui Dong, Aifeng Zhou, and colleagues investigated whether another typical human activity has influenced fire history in the areas along the Silk Road: war.
Ancient Warfare and Fire Use
Fire was a notable weapon in ancient Chinese warfare. Sun Tzu, the famed 5th-century BCE military strategist and author of “The Art of War,” recommended using fire against enemies. This historical context provides a backdrop for the study’s findings.
Scientific Investigation of Fire History
The research team measured black carbon, soot, and char in sediments from a core of Tianchi Lake, which represent 6,000 years of sediment deposition. The authors calculated the spatial range of land that would have contributed fire-related particulate to the sediment using the potential source contribution function analysis, a method typically used to determine the source areas for contemporary pollution.
Findings on Fire Frequency and Cause
Fire was infrequent in the middle Holocene, but became more frequent in the late Holocene, as the climate became drier and flammable herbaceous vegetation spread. Then, 2,000 years ago, the fire frequency became decoupled from climate or vegetation.
On centennial timescales, fires during this period are synchronous with warfare, as recorded in the List of Wars in Historical China. From 2,000–400 years ago, warfare between different political powers may have been the dominant contributor to high-intensity fires in the area, according to the authors.
Reference: “Warfare impact overtakes climate-controlled fires in the eastern Silk Roads since 2000 B.P.” by Shanjia Zhang, Hao Liu, Gang Li, Zhiping Zhang, Xintong Chen, Zhilin Shi, Aifeng Zhou and Guanghui Dong, 19 December 2023, PNAS Nexus.