What are the characteristics of the geographical environment in the middle and lower reaches of the Yangtze River during the Warring States Period?

The climate was warm during the Spring and Autumn Period and the Warring States Period, and continued to be mild during the Qin and Western Han Dynasties; by the Eastern Han Dynasty, that is, at the beginning of AD, the weather in my country tended to become colder, but the cold period in the Eastern Han Dynasty did not last long, and the climate during the Wei and Jin Dynasties was already cooler than during the Wei and Jin Dynasties. It's cold now. However, judging from the "Chart of Temperature Changes in China over the Five Thousand Years" attached to Zhu Wen, during the Warring States, Qin and Han Dynasties, the temperature generally showed a downward trend. The cooling process consisted of two stages: First, the climate fluctuations that began before the Warring States Period , the temperature dropped from about 2℃ higher than today (the temperature in the early Warring States period was about 1.5℃ higher than today) to only 0.5℃ higher than today in the late Warring States period. Afterwards, the temperature rose. Around 50 AD, the temperature rose to about 1.5°C higher than today, returning to the temperature level in the early Warring States Period. Another temperature drop event occurred around 50 AD. This process lasted until the late Eastern Han Dynasty, when the temperature down to today's temperature levels. Generally speaking, the temperature fluctuation range during the Warring States, Qin and Han Dynasties was about 1.5°C①. It is undeniable that the existing results, especially Zhu Kezhen's research, are of extremely high academic value, and its relevant conclusions have been confirmed by further in-depth research in the academic community. Such as Zhu Mingdao②, Wang Kafa③, Wang Zijin④, etc.

However, Zhu Kezhen’s conclusion is not flawless. It has been challenged by different research fields in the academic world. Researchers have written articles or pointed out the flaws and shortcomings of Zhu’s article⑤, or drawn conclusions about Zhu Kezhen’s conclusion. Quite different conclusions ⑥. At the same time, other scholars also have large differences in their research conclusions. Specific to this study, Zhang Piyuan believes that during the Qin and Han Dynasties, the climate in the middle reaches of the Yangtze River was still dominated by subtropical climate, with warm and humid climate, and subtropical forests and moso bamboo forests were widely spread⑦; Zhang Tianlin’s research results on the historical climate of the Yangtze River Delta show that from the Spring and Autumn Period to the Eastern Han Dynasty, The climate was warm in the later period, and people generally believe that the cooling that began in the early AD occurred after 200 AD in the delta area. However, Yang Huairen and others regarded the early Warring States period as a turning point in environmental changes in most areas of the country, including the middle and lower reaches of the Yangtze River. , believed that around this time, my country's climate changed to warm, cool and dry⑨; when Tang Lingyu et al. studied the Holocene climate in the Dongting Lake area and Jianghan Plain, they believed that since the Warring States Period, the climate in this region has gradually deteriorated and tended to be cold. Do ⑩.

The author takes the middle reaches of the Yangtze River Basin as the object and makes a preliminary discussion on the climate conditions during the Warring States, Qin and Han Dynasties (475-220 BC). Due to the limitation of records in ancient documents, in addition to classic records and archaeological materials, the documents based on this article mainly include pollen, sedimentation and peat data from relevant research results.