From the late Quaternary Pleistocene, about 1. 1, 000 years ago, the earth entered the modern subglacial period from the latest subglacial period of the Quaternary Glacier, also known as the post-glacial period. This period of time is roughly equivalent to the recorded historical era of mankind. About the climate of this period, Norwegian glaciologists made a snow line of nearly 10000 years. It shows that the snow line fluctuates greatly, indicating that the climate has changed obviously since the late glacial period. China has a long history. After sorting out and analyzing these records, Zhu Kezhen found that there have been four warm periods and four cold periods in the climate of China for more than 5,000 years.
The first warm period was from 3000 BC to 1000 BC, that is, from Yangshao Culture Age to Anyang Yin Ruins Age. In most of this period, the annual average temperature was about 2℃ higher than it is now, and the temperature in Leng Yue was about 3℃-5℃ higher than it is now.
From about 1000 BC to 850 BC (the beginning of the week), there was a short cold period, and the annual average temperature was below 0℃.
From 770 BC to the early AD, that is, the Qin and Han Dynasties, it entered a new warm period.
From the early AD to 600 AD, namely the Eastern Han Dynasty, the Three Kingdoms and the Six Dynasties, it entered the second cold period.
The period from 600 AD to 1000 AD, namely the Sui and Tang Dynasties, was the third warm period.
1000 to 1200, that is, the southern song dynasty was the third cold period, and the temperature was about l℃ lower than that of modern times.
From A.D. 1200 to A.D. 1300, that is, from the end of the Song Dynasty to the beginning of the Yuan Dynasty, it was the fourth warm period, but this time it was not as warm as that in the Sui and Tang Dynasties, which showed that elephants gradually moved from the Huaihe River basin to the south of the Yangtze River basin, such as Zhejiang, Guangdong and Yunnan.
1300 years later, that is, since the Ming and Qing dynasties, it is the fourth cold period, and the temperature is 1-2℃ lower than that of modern times.
In the past 5,000 years, although cold periods and warm periods appear alternately, the general trend is from warm to cold. The cold period is longer and colder every time. During the second cold period, only the Huaihe River froze in 225 AD. During the fourth cold period, the Yangtze River was almost frozen at 1.670.
Interestingly, Norwegian glaciologists use the height of the snow line to indicate the rise and fall of the temperature, while Zhu Ke uses historical documents to record the data, but the results are very consistent, indicating that the climate change since the late ice age is universal all over the world, which is definitely not a coincidence.
1973, Zhu Kezhen put forward the basic situation of the periodic climate fluctuation in the historical period of China. He believes that in the past 2000a years, the Han Dynasty was a warm period, and soon after the beginning of the Three Kingdoms, the climate became cold, which was postponed to the early Tang Dynasty. After the end of the Tang Dynasty, the climate became cold again, and gradually entered the Little Ice Age in the15th century, showing a structure of two peaks and three valleys, until the climate became warmer in the early 20th century. The little ice age is over. The Han Dynasty and the Tang Dynasty were warm periods when the annual average temperature was about 2℃ higher than that of modern times. The research results are widely used by climatologists and historical geographers. But in recent years, due to the discovery of new materials and the improvement of research methods, many scholars have supplemented Zhu Kezhen's work. Among them, Zhu et al. thought that the climate change in China's historical period since 2000-3000 had gone through the following stages: ① The climate in the Western Zhou Dynasty (6544 BC) was cold and dry. ② Warm and humid climate from the Spring and Autumn Period to the early Western Han Dynasty (from the middle of the 8th century BC to BC 1 century BC); ③ The cool and dry climate from the late Western Han Dynasty to the Northern Dynasty (65438 BC+the middle of the 0 th century to the 6 th century); ④ Warm and humid climate in Sui and pre-Tang period (7th-8th century); ⑤ The cool and dry climate from the late Tang Dynasty to the Northern Song Dynasty (9 ~ 1 1 century); ⑥ The dry and wet climate in the early Jin Dynasty (12nd century); ⑦ The cool and dry climate at the end of Jin and the beginning of Yuan (13 and the first half of 65438+4th century); ⑧ The cold and dry climate in Ming and Qing Dynasties (1the second half of the 4th century to the beginning of the 20th century). Later, many geographers made further modifications to the climate change in China, but the general trend was roughly the same.
The climate in the historical period not only has periodic fluctuations in temperature, causing changes in temperature and humidity, but also has certain changes in humidity. Generally speaking, warm period and wet period, cold period and dry period are corresponding, but each cold and warm period has wet and dry fluctuations, which cannot be generalized. Zhu and others believe that the temperature changes faster than the precipitation, while the precipitation changes more than the temperature. In the historical period, the climate changed in terms of temperature and humidity.
Human beings affect the climate, and the climate also affects human beings. Short-term climate change, especially extreme abnormal climate phenomena, such as drought, flood, freezing injury, hail, sandstorm, etc. , often lead to serious natural disasters, enough to bring a devastating blow to human society. For example, the rainstorm disaster from 1943 to 1954 in Bangladesh caused the biggest famine in the 20th century. 1968-1973, the drought in Africa is a huge disaster for the African people. It has caused 70-90% livestock losses in Chad, Niger and Ethiopia, and 200,000 people have starved to death in Wolo province of Ethiopia alone. Of course, this kind of attack is often short-lived and partial. Although it has not affected the ecosystem, it has caused great harm to human beings.
Long-term climate change, even if the change is slow, will fundamentally change the ecosystem, completely change the production layout and mode, and then affect the economic life of human society.
For example, during the warm period of 3000- 1000 BC, bamboo was widely distributed in the Yellow River basin to the eastern coast; There are tropical and subtropical animals such as buffalo and wild boar found in Yin Ruins in Anyang. Oracle Bone Inscriptions recorded an elephant that was hunting, indicating that the elephant fossils in Yin Ruins are native. Henan, formerly known as Yuzhou, is a symbol of people holding elephants. In Shang and Zhou dynasties, plums were an important daily food for people in the north. The Book of Songs says, "If you make soup with salt, you will only find salt in plums." It can be seen that plums were as important as salt at that time and were indispensable seasonings for cooking. The Book of Songs says, "What is the end of the South?"
The climate in Qin and Han dynasties was also warmer. According to historical records, the geographical distribution of cash crops at that time was "the orange in Jiangling, the mulberry in Qilu, the bamboo in Weichuan and the paint in Chen Xia". It can be seen that the boundary of subtropical plants was farther north than it is now.
Because climate change directly affects the geographical distribution of crops, it will inevitably affect the industrial layout with agricultural products as raw materials. For example, before the pre-Qin and Western Han Dynasties, the layout of China silk industry was north silk and south hemp, and most of the silk industry was in the middle and lower reaches of the Yellow River and the Central Plains of Hebei Province. At that time, the largest silk industrial center was located in Dingxian County, Hebei Province, and other smaller centers were also located in Hebei, Henan and Shandong, while the Yangtze River Basin and the southern region mainly produced hemp fabrics. During the Western Han Dynasty, Shu was only famous for producing flax. Although there were frequent wars in the Central Plains from the Eastern Han Dynasty to the Wei and Jin Dynasties, the economy declined sharply, the social life in the southern region was relatively stable, and the silk weaving industry was developed, but the layout of North Silk and South Hemp remained until the Sui and Tang Dynasties. Judging from climate change, the average temperature is still warmer than in modern times, which shows that the Silk Road appeared in the north for a reason.
The change of the layout of North Silk and South Hemp occurred in the Song Dynasty. Due to the cold climate, the temperature in the north is lower than that in modern times, which is not conducive to silkworm production and reproduction. Coupled with the war in the north in the late Tang Dynasty and the Five Dynasties, the economy in the south rose, and the scale of silk weaving industry gradually surpassed that in the north. In the Northern Song Dynasty, Zhenjiang and Santai had become the national silk weaving centers. During the Southern Song Dynasty, Nanjing, Changzhou, Zhenjiang and Suzhou all had huge silk production capacity. The center of gravity of silk industry moves south, which is exactly equivalent to the center of gravity of China.
Climate change has also had an impact on agriculture. Mencius (372- 289 BC) and Xunzi (365,438+03-238 BC) both said that agricultural planting in Qi and Shandong (Hebei and Shandong) could be planted twice a year. Until the early liberation, they were only used to planting three crops every two years. The growing season in the Tang Dynasty was also longer than now. Harvest two seasons a year, rice in September and wheat or barley in April. However, due to the shortened growing season, peas and broad beans have to be planted instead of wheat and barley in modern times. This historical experience is still of practical significance today. For example, if the climate is warming, double-cropping rice can be considered to expand to high latitudes and high altitudes; If the climate gets cold, measures must be taken to shorten the growth time of rice.
First, the time difference
Climate includes two basic elements: temperature and dry and wet conditions, and the study of historical climate must also start from these two aspects. The article "Preliminary Study on Climate Change in China in the Last Five Thousand Years" by the famous scientist Mr. Zhu Kezhen (①) systematically summarizes the basic laws of climate change in China, indicating that the temperature change in China in the last five thousand years has four warm periods and four cold periods.
1. The first warm period was from 3000 BC to 1 100 BC, that is, from Yangshao culture period to Yin and Shang dynasties. Oracle Bone Inscriptions recorded that Anyang rice was planted in February of the lunar calendar at that time, more than a month earlier than now. The analysis of the peat layer near Beijing shows that a large number of broad-leaved forests grew there 5,000 years ago, representing a fairly mild climate.
2. The first cold period was from 1000 BC to 850 BC, that is, the cold period of the Western Zhou Dynasty. The Chronicle of Bamboo Records records the freezing of the Yangtze River and Hanshui River in the Zhou Dynasty, indicating that the climate at that time was colder than it is now.
3. The second warm period is from 770 BC to the beginning of AD, that is, from the Eastern Zhou Dynasty to the Qin and Han Dynasties. Spring and Autumn Annals records that there is no ice in the first month of spring, no ice in February, no ice in spring and so on. According to Xunzi Guo Fu and Mencius Gaozi, agricultural cultivation in Qilu area is twice a year.
4. The second cold period lasted from 1 century to 600 AD, that is, the cold period of the Eastern Han Dynasty and the Southern and Northern Dynasties, and reached its peak in the first half of the 4th century AD. In the early years of the Jin Dynasty, the Bohai Bay was completely frozen from Changli to Yingkou for three consecutive years, and thousands of horses and chariots could drive on the ice, and the annual average temperature was 2-4℃ lower than now.
5. The third warm period is from 600 AD to 1000 AD, that is, the Sui and Tang Dynasties. During this period, there was no ice and snow in the winters of 650 AD, 689 AD and 678 AD, and the climate was warm and visible.
6. The third cold period is from 1000 to 1200, which is the Song Dynasty. During this period, Taihu Lake11was completely frozen and opened to traffic on ice, 1 165438.
7. The fourth warm period is 1200 ~ 1300, that is, the warm period in the late Song Dynasty and early Yuan Dynasty. 1225, Qiu Chuji, a Taoist, wrote a poem in Changchun Palace, Beijing, which said: "During the Qingming Festival, apricot blossoms bloom and thousands of families come and go." This shows that the climate in Beijing was warmer then than it is now.
8. The fourth cold period is from 1300 to 1900, that is, the cold period of Ming and Qing Dynasties. During this period, Taihu Lake froze for several feet at 1329, and oranges froze to death. During the period of 1493, heavy snow fell in the Huaihe River Basin, and Dongting Lake became an "ice sheet" from September of that year to February of the following year.
In the past five thousand years, the climate in China has changed alternately from four warm periods to four cold periods, and the time difference is very obvious.
Second, the spatial differences.
There are four factors affecting climate change in historical period: solar radiation, underlying surface, atmospheric circulation and human activities. The interaction of these factors determines the climate change. In addition, China's latitude position, land and sea position, vast area, complex terrain and circulation factors that dominate climate determine another feature of climate change in China-the emergence of spatial differences.
The climate fluctuation on the earth is first related to the intensity of solar radiation. The cycle of spring, summer, autumn and winter, the difference of cold, warm and hot areas are all due to the different intensity of solar radiation. China's territory starts from the middle reaches of Heilongjiang River in the north and reaches Zengmu shoal in the south, which spans 49 latitudes from north to south. From south to north, it includes six hot zones: equatorial belt, tropical zone, subtropical zone, warm temperate zone and cold temperate zone.
From the land and sea position, China is located between Asia-Europe continent, the largest continent in the world, and the largest ocean Pacific Ocean. Due to the different surface heat conditions, different temperature fields and pressure fields are formed, resulting in obvious monsoon circulation, which has a far-reaching impact on China's climate. Compared with the same latitude regions in the world, the Yellow River Basin in China is equivalent to the Mediterranean region, and the latitude south of the Yangtze River is equivalent to sub-Saharan Africa in North Africa. Jiangnan in China is a desert, but due to the subtropical monsoon climate, the eastern and southern parts of China have become unique areas with the richest subtropical natural resources in the world with high temperature and abundant precipitation.
From the east-west trend of the three mountain systems in China, they are the barriers of cold and warm air flow between the north and the south, and constitute an important climate dividing line. Among them, the Qinling Mountains with an altitude of 1500-2500m have the most obvious influence. The northern part of Qinling Mountains is warm temperate zone and the southern part is subtropical zone. The poem "Shan Mei opens in October, and the southern branch is warm in the north and cold in the south" just shows that Qinling Mountain is the climate dividing line between the north and the south of China. It is 5000 meters above sea level. The humid climate in the Pacific Ocean is not available, and the water vapor channel from the Indian Ocean is cut off by the Himalayas, which makes the northwest inland of China a desert arid climate. In addition, Siberian cold air suddenly invaded from the Mongolian Plateau, forming a strong cold wave that affected most parts of northern China in winter, which increased the spatial difference of climate change in the east, west, north and south.
In China, the climate is getting colder from south to north and from east to west, and forests, grasslands, barren sand and deserts also appear in turn, thus forming a completely different climate from east to west, north and south. The biggest feature is the natural differentiation of climate in the southeast and northwest. The spatial and temporal differences of climate change alternate, which has a great impact on the historical development of China in different periods.
Third, the influence of time and space differences.
The first is political influence.
The division between the southeast and northwest of China caused by the difference of climate in time and space has had a far-reaching impact on the social development of China. Modern geographers draw a diagonal line on the map of China, with the northwest of China to the west, accounting for 57. 1% of China's land area and 5.6% of the total population. Historically, it is generally the main activity area of nomadic people or ethnic minorities. To the east and south of the diagonal is the southeast of China, occupying 42% of the territory and 94% of the total population. It is basically the main activity area of agricultural nationalities (Han nationality) in history. (2) Among them, with the change of climate, the economy and culture in the southeast gradually surpass that in the north, and the population density is also increasing.
Between the northwest and southeast of China, the ancient Great Wall generally coincides with the natural dividing line between agricultural and pastoral areas. As early as 1 12 1 years ago, Taoist Qiu Chuji said when crossing Yehuling, the first pass in Zhangjiakou in the north, "Looking up and overlooking Taihang Mountain, it is sunny and lovely. Looking north, it is cold sand and cold grass, and it has been isolated from the wind of the Central Plains since then. " "Between the desert, it is freezing, windy, livestock and fish feed, fur is clothes, and people can change their disciples at any time, so horses and chariots are home. This geographical environment determines the confrontation between farming, animal husbandry and agricultural peoples and nomadic peoples in the history of China. Two economies, two nationalities, communicate peacefully with each other and wait for each other. Whenever the cold period replaces the warm period, there are always large-scale nomads going south to keep warm. The agricultural dynasty in the Central Plains is facing the challenge of nomadic people in the north. Among them, the "Five Wild Flowers" around 400 AD, the Khitan, the Nuzhen and the Mongols went south one after another around 1200 AD, and the Manchu entered the customs around 1700 AD, which is the most typical example of the military conflict between the farming and pastoral peoples. The war and relationship between the Central Plains Dynasty and the northern minority regimes have always influenced and restricted the social and historical development of China.
The confrontation between farmers and herdsmen has the most direct influence on politics. With several biggest military conflicts, there have been several typical political situations of confrontation between the Northern and Southern Dynasties. "Five Wild Flowers" accompanied the confrontation between the sixteen northern countries and the Northern Wei Dynasty, the Northern Qi Dynasty, the Northern Zhou Dynasty and the Southern Eastern Jin Dynasty, the Song Dynasty, the Qi Dynasty, the Liang Dynasty and Chen Dynasty. Along with the southward migration of Khitan, Nuzhen and Mongolia, it was the second confrontation between the Southern and Northern Dynasties and the Liao, Jin and Song regimes. In the Ming Dynasty, the regime in the early Ming Dynasty confronted the regime in the Northern Yuan Dynasty. Then there is the confrontation between the Nanming regime and the Qing regime in the late Ming Dynasty. Due to the long-term confrontation between the North and the South, the agricultural people had to rely on the authoritarian centralized government to organize scattered farmers to build the Great Wall of Wan Li to defend their lives and live and work in peace and contentment, which is one of the important reasons for the long-term existence of authoritarian centralization of authority in China.
The second is the economic impact.
Five or six thousand years ago, it was a very humid climate at the same time as the warm period. At that time, the Heilongjiang River Basin was the wettest period for thousands of years, and the Beijing Plain was the hometown of rivers and ponds. About 2500 years ago, the climate became dry. During the archaeological excavation in Beijing, it was found that the mixed carbon swamp, which represents the humid climate, gradually disappeared. About 1000 years ago, the climate dried up again. According to a large number of local chronicles, since the beginning of A.D., with A.D. 1000 as the boundary, floods in southeast China have decreased relatively, while droughts have increased relatively. Prior to this, the drought period in 1000 was short and the wet period was long. Since then, the rainy period is short and the dry period is long. The chronology of drought and flood data in recent 500 years shows that drought is obviously more than flood.
The dry and wet change of climate has a great influence on agricultural production, and agricultural production in arid and cold areas is seriously restricted. Needless to say, in other areas, the development of agricultural production is also affected by cold, warm, dry and wet climate changes. Generally speaking, every time the temperature drops by 65,438 0℃, the position of the subtropical northern boundary moves south by about one latitude. The northern boundary position suitable for crop growth has also moved southward. In the past five thousand years, the general trend of climate fluctuation in China is that the warm period is short and the warmth is low, which determines the general trend that the economic center of gravity based on the agricultural economy as a whole moves southward. In the history of China, the economic center of gravity moved southward mainly in three periods: Wei, Jin, Southern and Northern Dynasties, economic stagnation and recession in the Yellow River basin, great development in the Yangtze River basin and economic rise in the south. During the Five Dynasties and the Song Dynasty, the southern economy rose and surpassed the northern economy, forming a new economic center of gravity, and the economic situation of "prosperity in the south and decline in the north" continued to develop; Since the Ming and Qing dynasties, the economic center of gravity has moved further south, the southeast coastal areas have developed abnormally, and the gap between the east and the west and the gap between the north and the south has further widened. Looking at the southward movement of these three economic centers, it coincides with the arrival of the second, third and fourth cold periods in history, and it is not difficult to see the relationship between geographical environment and economic development.
Thirdly, it is cultural influence.
Economy is the foundation, and its change determines the change of superstructure. With the shift of the economic center of gravity to the south, the culture in the superstructure will inevitably change greatly. The most obvious performance is that before the Sui and Tang Dynasties, the economic center of China was in the north, and after the Sui and Tang Dynasties, the cultural center was also in the north, and the economic center shifted to the south accordingly.
During the Qin and Han Dynasties, Guanzhong was the capital, and the economic and cultural center of gravity was in the Yellow River basin. There is a saying that "Shandong is the leader, Shanxi is the leader", "Kansai is the leader and Kanto is the leader". After the Sui and Tang Dynasties, food supply began to depend on the south, and the cultural center of gravity began to move south. In the Song Dynasty, there was a saying that "Su Changshu was the best in the world" and "Jiangsu and Zhejiang were the best in the world". In the Ming and Qing Dynasties, China's culture was based on the richest Yangtze River valley, forming a situation of "one in the southeast, one in Jiangsu and Zhejiang". Since modern times, with the development of coastal economy, Guangdong and Fujian have gradually occupied an important position in the economy, and China culture has a tendency to move further south.
As for the shift of China's cultural center of gravity to the south, predecessors mostly studied it from the aspect of "the geographical distribution of China's historical figures". Two families are introduced here to illustrate the relationship between culture and geographical environment. In the article "The Relationship between Historical Figures and Geography" (③), Ding Wenjiang listed the figures of the provinces according to the generations of Han, Tang, Song and Ming in the twenty-four histories:
Before Han Dynasty, after Han Dynasty, Tang Dynasty, Northern Song Dynasty, Southern Song Dynasty, Ming Dynasty
The provinces with the largest population are Shandong, Henan, Shaanxi, Henan, Zhejiang and Zhejiang.
Henan, Shaanxi, Hebei, Fujian and Jiangsu
In the article "Observing the North and South Cultures of China from History" (④), Japanese Sang Yuan took the imperial examination as an example and submitted the statistics of the number of people who passed the imperial examination in Ming and Qing Dynasties. From the fourth year of Hongwu in the Ming Dynasty to the forty-fourth year of Wanli, there were 244 people who won the top prize, ranked first, explored flowers and made friends in various subjects, including 2 15 in the south, accounting for 88%. 42 of them are from the south. In the first year of Qianlong, * * * takes sixty-five thousand four hundred and thirty-eight+zero five, and sixty-five thousand four hundred and thirty-eight+zero four in the south. In the Ming and Qing Dynasties, * * * took 203 students, and the South took 188 students.
Four. Discussion on related issues
1. By discussing the characteristics and impacts of climate change in China, we can further understand the role of geographical environment in historical development. How to treat the relationship between geographical environment and historical development is an old and often new topic. In the past, due to the one-sided criticism of "geographical environment determinism", the role of geographical environment in historical development was rarely discussed in detail. In recent years, through various studies and discussions, people realize that the geographical environment itself is a part of human society and its historical development. When transforming the natural environment, human beings should not violate the constraints of natural laws, otherwise they will be punished by natural laws. But what is the relationship between geographical environment and the development of human society? What influence does the geographical environment have on the development of social history? How great will the impact be? There are still different opinions on these issues. Through the analysis of this paper, we can first affirm that the influence of geographical environment on social history is a historical category. With the evolution of the times, its function mode and degree are constantly changing. Therefore, we should attach importance to the study and research of historical geography. Why is the feudal society in China particularly long in the study of China history? Why is the embryonic development of capitalism extremely slow? Many comrades believe that geographical conditions are the most fundamental factor. Specifically, the characteristics of geographical environment at home and abroad and the corresponding social production mode not only produced the demand for authoritarian regime, but also maintained the prosperity of feudal small agriculture, which made it difficult for China to have the objective conditions for the transition to capitalism, thus leading to the long-term continuation of feudal society in China. Are these views correct? We still need to make a thorough and detailed study of the historical geography of China before we can draw a conclusion.
Secondly, through the above analysis, we also realize that human history and geographical environment are a unity, they restrict and interact with each other, and this mutual restriction and interaction shows different forms in different times and regions. Generally speaking, the lower the level of productivity, the greater the restriction of human beings by geographical environment; The older the stage of social development, the greater the dependence of human beings on the geographical environment. In ancient China, the temporal and spatial differences of climate change influenced the development direction of politics, economy and culture, which showed that the geographical environment really promoted or delayed the history of China, especially the opposition between the minority regime and the Han regime in the history of China (Qin and Han Dynasty and Xiongnu, Eastern Jin and Southern Dynasties and "Five Lakes", Song and Liao Dynasties, Jin Dynasty, Ming Dynasty and Mongolia, Manchu Dynasty, etc.). ). They are all caused by the opposing environmental factors in agricultural and pastoral areas caused by the differences in climate time and space. With the development of social productive forces, especially the progress of science and technology, human society has increasingly restricted the geographical environment that can provide more material wealth for human beings. However, this does not mean that the role of geographical environment has decreased. Due to the role of human beings in the geographical environment, the geographical environment has changed and formed a new geographical environment system. In addition to the original natural environment, the economic environment and human environment system have been added, which has had a new impact on human society. In the modern climate change in China, we have to explore the new changes and new influences of human environmental pollution, which determines the guiding significance of studying historical geography to reality and practice.
2. By discussing the characteristics of climate change in China's history, we can further understand the disciplinary nature of historical geography. Historical geography is an ancient and young discipline, and there are different views on its nature in academic circles. At present, the history department and some geography departments of domestic universities have offered the course "Historical Geography of China". However, due to different views on its subject attributes, the teaching content, learning focus and research direction are quite different. Some people think it is a branch of history. Some people regard it as a branch of geography, emphasizing the discussion of natural phenomena and their laws in historical periods; Some people regard it as an interdisciplinary subject of history and geography, focusing on interdisciplinary research.
We believe that historical geography is not only an interdisciplinary subject between history and geography, but also an interdisciplinary and interrelated comprehensive subject in natural science and social science. Historical geography not only studies the natural process of natural environment change, but also studies the man-made process of transforming natural environment change. More importantly, it focuses on the changing law of the relationship between man and land in historical period. It cannot be simply summarized as a branch of history or geography, but a new interdisciplinary system. As Zhekulin, a historical geographer in the former Soviet Union, said, it is not only a marginal discipline formed by the combination of geography and history, but also "closely related to a series of scientific categories such as ethnography, toponymy and agricultural history in its own development process." Therefore, accurately speaking, it is "a comprehensive discipline on the edge of natural science and social science, and its main task is to study the regularity of social and natural's interaction." Based on this understanding, our vision of historical geography research will gradually broaden.
The nature of the discipline determines the research methods of the discipline. The world is a whole, and nature and human society are inseparable. Modern science and technology have reached the stage of mutual penetration and integration among disciplines, and historical geography has emerged to meet the requirements of this era. Therefore, it inevitably requires us to master the knowledge of different disciplines and carry out creative research on the basis of the cross-study of social science and natural science. If this analysis can play a role in attracting jade, the purpose will be achieved.