Shanjia Zhang

Investigating the intricate connection among the combustion types (smoldering v.s. flaming), human activity and climatic patterns is is crucial for understanding the mechanisms of paleo-fire occurrences. This interaction requires further clarification, especcially in the NE Tibetan Plateau, due to the dramatic climatic and human activity shifts during the mid-late Holocene. Here, we examined the black carbon (BC, comprising char and soot) content within sediments from Caodalian (CDL) lake spanning the past 7600 years. The findings indicate paleo-fire intensity was consistent with variations in combustion types revealing by the ratio of char/soot on different timescales during the mid-late Holocene. An integrtated paleo-fire index shows that the fire activity underscores a pattern of low middle Holocene and rapidly increasing late Holocene fires, with two distinct peaks occurring during the Bronze Age and historical period. This variation aligns with the shifts observed in the char/soot ratio, indicating that enhanced flaming fires were more prevalent during the late Holocene. A comparative analysis of regional paleo-climate data has revealed that the progressive aridification of the climate, along with rising spring temperatures, contributed to the increase in paleo-fires. And the expansion of grasslands likely fueled the rise in flaming fires, thereby intensifying paleo-fire activity. Notably, we contend that human fire practices heightened the incidence of late Holoceng regional flaming fires, which in turn contributed to the intensification of paleo-fire regimes. High-intensity human activities (e.g. land reclamation, pottery production, bronze crafting) that have been prevalent since 4000 BP, along with the increased warfare since 1200 BP, were significant factors behind this outcome.

Flooding and warfare were important challenges to the development of human societies in the Late Holocene, especially in flood-prone areas, including the Bailongjiang Basin in the northeastern Tibetan Plateau. It is not clear how ancient societies in this region fought against flooding and war, and its study is an important way to explore the patterns of human-environment interactions. In response to these questions, a detailed survey of ancient cities in the upper Bailongjiang River during the historical period was carried out, and 42 dating samples were collected from six ancient cities and one site. The results showed that these ancient cities were mainly built during the Tang and Qing dynasties. Among them, a unique three-dimensional defence system was discovered for the first time in the investigation and research in the area of the ancient city of Diezhou, including city walls and water retaining walls from the Sui and Tang dynasties, as well as enclosure walls and beacon flints from the Qing dynasty. A combination of geomorphological surveys, historical documents, and paleoclimatic data suggests that ancient humans constructed the three-dimensional defence system in this area mainly in response to high-frequency flooding triggered by climate change, as well as wars between the Tang and Tubo, and between the Qing and the Heshuit Khanates. This study provides a typical example of human-water-war interactions during the historical period in the high mountain valley area of the northeastern Tibetan Plateau, which is of great academic value for the in-depth understanding of the process and mechanism of the evolution of human-earth relations in the high mountain valley area.

The history of Holocene fire evolution and its influencing factors are hot scientific issues. The middle (Xinjiang) and eastern (Xi'an-Dunhuang) parts of the Silk Road were affected by different climatic systems, and there are obvious differences in the mode and intensity of human activities in the middle and late Holocene. Research on the history of paleo-fires in this region and their relationship with climate change and human activities has received extensive attention. Based on the analysis of black carbon in the sediments of two alpine lakes, and combining the available paleo-climatic results, archaeological and historical literature, we reconstructed the paleo-fire history of the middle and late Holocene in the area. We revealed the relationship between paleo-fires and the changes in climate, vegetation, and human activities in different regions, and explored the differences in the patterns of paleo-fires in the study area in terms of temporal and spatial variations, and their possible driving mechanisms. The above work will help to understand the pattern and mechanism of ancient fires in the mid-eastern Silk Road on a centennial and millennial scale, which is of great theoretical value and practical significance for future fire prevention and control measures in the context of climate change, and also provides a valuable case study for understanding the impact of human activities on the environment.

Warfare has played an important role in fire regimes; however, it remains unclear whether and when it may have impacted fire history along the Silk Roads. Based on a high-resolution record of black carbon in alpine-lake sediment, and warfare data from historical documents, we explore the relationships between fire, fuel, climate, and human activity along the eastern Silk Roads over the past 6,000 years. Results show that fire activities were low in the middle Holocene but gradually increased in the late Holocene, a pattern closely related to the intensification of drought and the expansion of herbaceous vegetation. However, the intensity and amplitude of paleo-fires increased significantly in the past 2,000 years, a pattern that was no longer synchronized with climate and vegetation changes on centennial timescales; rather, the sequence demonstrated a significant positive correlation with the documented number of wars in different dynasties. We argue that warfare between different political powers may have been the primary influence on the occurrence of five high-intensity fires since 2000 B.P. on centennial timescales in the eastern Silk Roads. Our study certainly reveals the impact of warfare activities related to dynastic change on fire regimes in Chinese history, providing a novel perspective for understanding the impact of human activities on the environment.

Coal has long fueled human civilizations. The history of systematic coal fuel exploitation has been traced back to the late third millennium before present (post-2500 B.P.). Although sporadic combustion of coal for fuel was reported in some prehistoric archaeological sites, evidence for the systematic exploitation of coal for fuel before 2500 B.P. remains lacking. Here, we report comprehensive understanding for the earliest systematic exploitation of coal for fuel at the Jirentaigoukou site in Xinjiang, northwestern China, at ~3600 B.P. The main body of the site witnessed systematic exploitation of bituminous coals, illustrating a complete chaîne opératoire with selective mining, planned storage, and extensive combustion. Our results transform the knowledge of energy history by extending the upper limit of the systematic exploitation of coal for fuel by approximately a millennium, and provide a precedent of energy transition under intense conflict between social demand and environmental deterioration.

The Gansu–Qinghai region lies in the key position for trans-Eurasian cultural exchange, and hence investigations of the history of agricultural development in this region are significant for understanding the spatiotemporal evolution of prehistoric crop dispersal in Eurasia. However, systematic archaeobotanical studies concerning the history of the development of prehistoric agriculture in this area are scarce. Here, based on archaeobotanical analysis and radiocarbon dating at the Jinchankou site, we investigated the history of agricultural development in the Datong River valley during the Qijia culture. Combined with previous archaeobotanical studies of the Gansu–Qinghai region, we explored the diachronic changes in the cropping patterns from the Late Neolithic to the Early Iron Age. The results suggest that millet remained the most important subsistence plant during 4100–3700 BP, while barley and wheat were first cultivated around 3900 BP at the Jinchankou site. Humans only cultivated foxtail and broomcorn millet in the Gansu–Qinghai region with a high level of agricultural management during 5900–4000 BP. Barley and wheat were added to the agricultural system in the area during 4000–3600 BP, although they played a subsidiary role compared with millet. During 3600–2100 BP, barley played an increasingly important role in the Gansu–Qinghai region but with evident differences among geomorphic units, and there was an obvious decrease in agricultural management level. It is likely that the transformation of cropping patterns and agricultural management levels in the Gansu–Qinghai region from 5900 to 2100 BP was primarily promoted by prehistoric trans-continental cultural exchange and secondly by climate change in the area.

The Proto-Shang, the Shang and the Zhou dynasties (∼2000–221 BCE: Before Common Era) are key periods in the origin and evolution of ancient civilizations in China since the periods include the processes and mechanisms of social development in the Central Plains of China during the Bronze Age. However, human-environment interactions in the context of trans-Eurasia cultural exchange during that time are not well-understood. In this study, isotopic analysis and radiocarbon dating of human and animal bones from Xinancheng cemetery in southeast Shanxi Province are reported. It was deduced that, for the period ∼1000–800 BCE, humans buried in Xinancheng cemetery relied primarily on C₄-based foods and upper-status individuals consumed more animal protein and probably C₃ crops. Also, considering the paleoclimate and other archaeological data of the Central Plains, the human diet and subsistence strategies changed significantly with more C₃ staples such as wheat being consumed during the Eastern Zhou (770–221 BCE), as evidenced by an increased intake of wheat by lower-status individuals and the development of a mixed wheat and millet agricultural system. It is argued that the socio-economic change around the late western Zhou-early eastern Zhou Dynasty occurred as a result of the necessity to adapt to the aggravation caused by climate deterioration and population pressures, factors which profoundly influenced the economic and lifestyle patterns in ancient China. The socio-economic system of the Eastern Zhou Dynasty displayed more resilience to climate change than that of earlier periods.