Animals and plants, nationalities, history near the Yangtze River,

Since Chinese civilization originated in the Yellow River Valley, most people in ancient China lived between the Yellow River Valley, the North China Plain and the middle and lower reaches of the Yangtze River (the Central Plains). Until the Northern Song Dynasty, the Central Plains was the foundation of the central government and the historical activity center of our Chinese ancestors. Therefore, in this paper, my analysis is centered on the Central Plains, first explaining the basic situation of the Central Plains itself, and then roughly explaining the geographical terrain around the Central Plains.

1, Central Plains-Basic situation of Loess Plateau, North China Plain and the middle and lower reaches of the Yangtze River

The Central Plains is a very important concept in the history of China, and its scope has changed greatly since ancient times. The word "Central Plains" has been used in spoken language by people at that time as early as the Spring and Autumn Period, but it originally meant "Plain" or "Yuan Ye". For example, "The Book of Songs Xiaoya Jiri" says: "Looking at the Central Plains, there are holes." The Book of Songs Xiaoya Xiaowan says: "There are cymbals in the Central Plains, and Shu Ren adopted them." The word "Central Plains" is mentioned in the above poem, and Mao's poem notes: "Central Plains was originally in China." Zheng Xuan wrote: "Huo was born in the original." Obviously, the so-called "Central Plains" actually refers to the plain or Yuan Ye, not the region. It was only in the late Spring and Autumn Period that the Central Plains evolved into a regional concept. "Zuo Zhuan Xi Gong Twenty-three Years" records: "Jin Chu governs the army and meets the Central Plains." "Sun Tzu's Art of War and War" also records: "Force is wasted, and the Central Plains is empty." Even later, Zhuge Liang's "Model": "The three armies awarded it, and it was originally scheduled to be in the north." "Biography of Wang Chengchuan, the Northern History Rencheng" said: "Therefore, the scale shines on the Central Plains." In the fourteenth year of Yongle in the Ming Dynasty: "Fu Weijing, south of the Central Plains." The "Central Plains" in the above five documents no longer refers to the plains or Yuanye, but refers to the plains in the middle and lower reaches of the Yellow River, which is different from the border areas. Of course, the geographical scope of the Central Plains has also changed gradually in the history of China. From the Spring and Autumn Period to the Han Dynasty, the Central Plains mainly refers to the eastern part of the Loess Plateau and the central part of the North China Plain. From the Tang Dynasty, the scope of the Central Plains expanded to the whole North China Plain and most parts of the Loess Plateau, and it did not include most parts of the middle and lower reaches of the Yangtze River until the Southern Song Dynasty.

The general geographical scope of the Loess Plateau is that it starts from the eastern end of Qilian Mountain in the west, reaches Taihang Mountain in the west, and connects with the Mongolian Plateau along the Great Wall in the north (the height of the Loess Plateau and the Mongolian Plateau is the same: the altitude is about 1000 meters, but the climate, soil and rainfall are quite different), and it reaches the Qinling Mountains in the south, with an area of about 500,000 square kilometers. The geographical conditions in the North China Plain are similar to those in the middle and lower reaches of the Yangtze River. Most areas are below 50 meters above sea level. The terrain is very flat and the traffic is quite convenient. It starts from Beijing and Tianjin in the north, reaches the Yangtze River valley in the south (including parts of central Hunan and northwestern Jiangxi), reaches Taihang Mountain in the west, Wushan Mountain in the west and the sea in the east. The total area is * * * 1 ten thousand square kilometers.

The Loess Plateau and the North China Plain are basically located in the warm temperate climate zone of China (the annual accumulated temperature is 3400-4500℃). In modern times, the annual rainfall is basically between 400 mm and 800 mm (belonging to semi-humid areas), and its crops are harvested three times a year or twice a year. The plain in the middle and lower reaches of the Yangtze River belongs to the subtropical climate zone in China (the annual accumulated temperature is 4500-8000℃), the modern annual rainfall is basically above 800mm (it belongs to the humid zone), and its crops are harvested two or three times a year.

2. Geographical terrain around the Central Plains

The geographical terrain of the Central Plains is quite unique in the plains all over the world. The Central Plains itself is huge in scale, but the surrounding geographical environment is harsh, forming a huge closed system. Let's take a look at the geographical terrain around the Central Plains.

North of the Central Plains is the Mongolian Plateau. Mongolia Plateau is connected with the Loess Plateau, and its height is almost the same as that of the Loess Plateau. Moreover, the Mongolian Plateau is the flattest plateau in China, and the traffic conditions are quite convenient. However, the climatic conditions are too bad, and the annual accumulated temperature in the Mongolian Plateau is only 1600-3400℃. From the west of Daxinganling to the north of the Great Wall to Lanzhou, including the Mongolian Plateau, the annual rainfall in modern times is only 200 mm -400 mm (semi-arid area). However, due to the climate limitation of the Mongolian Plateau and the backward production technology of ancient animal husbandry, the population living on this 4 million square kilometers land has been around 6.5438+0 million, and there has been no amazing growth. The population size "can't reach a county in Han Dynasty". Further north, the Mongolian Plateau belongs to the inaccessible Siberian Plateau, which has been a difficult area for human beings to survive since ancient times. Since the Western Zhou Dynasty, nomadic people in the Mongolian Plateau began to harass the dynasty regime in the Central Plains, but it has always been a small-scale guerrilla nature. It was not until the "Five Chaos" period that these nomadic people began to enter the hinterland of the Central Plains.

To the west of the Central Plains is the vast Qinghai-Tibet Plateau, the highest plateau in the world, with an average elevation of 4,000 meters. Himalayas, the highest mountain in the world, is also distributed in its southwest. The Qinghai-Tibet Plateau covers a total area of more than 2.5 million square kilometers, with a cold climate and extremely inconvenient transportation. From millions of years ago to today, there has never been a war of barbarians attacking the Central Plains based on the Qinghai-Tibet Plateau in the history of China. The climate of the Qinghai-Tibet Plateau has always restricted the growth of the local population, and the inconvenient transportation has also made it difficult for it to wage war against the Central Plains effectively.

In the northwest of the Central Plains, it belongs to the Western Regions. The area is connected with the Central Plains by a long and narrow road (composed of Hetao Corridor and western oasis) sandwiched between the Qinghai-Tibet Plateau and the Mongolian Plateau. However, because the vast areas in the Western Region belong to arid areas (wetter before the Han Dynasty than now), the desert area is too large, and the population and civilization level have not been vigorously developed, so there has never been a powerful force threatening the Central Plains regime in the Western Region. Its weak strength made it either a nomadic people attached to the Mongolian Plateau or a dynastic regime obedient to the Central Plains in the history of China.

In the south of the Central Plains, that is, the hilly areas in the southeast of China, the annual accumulated temperature and rainfall are much stronger than those in the Loess Plateau, the North China Plain and the Yangtze River Plain, which is very beneficial to the development of agriculture from the climate point of view. Moreover, primitive human activities appeared in this area very early and entered the era of civilization earlier. 10000 to 6000 years ago, quite a few ancestors of China once lived here. But why hasn't such a large area developed into the center of Chinese civilization? This is related to the local geographical traffic conditions. There are many mountains in hilly areas, which are much lower than the Qinghai-Tibet Plateau. However, the mountains here have seriously restricted human communication under the condition that the ancient means of transportation are backward. Therefore, the ancient civilizations in the hilly areas of southeast China have always been divided by geographical environment and distributed in points. There is a lack of sufficient communication and mutual promotion between primitive civilizations, and the progress of civilization is slow. Moreover, there are many birds, animals, insects and snakes in the south of China, and there are many diseases. The population has not been effectively increased, so that it has not been able to form a large-scale unified whole like the ancient civilization in the Central Plains for a long time.

As for the east of the Central Plains, just look at the map and you will know what it is, Bohai Sea, Yellow Sea, East China Sea and South China Sea. Except for the Japanese invaders of the Ming Dynasty and the invasion of China by modern western powers from the sea, the Central Plains region has never been threatened by the East.

Due to the particularity of the geographical environment around the Central Plains, the Central Plains (Loess Plateau, North China Reduction, Middle and Lower Yangtze Plain) has been in a relatively closed vast area for a long time. This has played a considerable role in protecting the growth and development of Chinese ancestors (before the Han Dynasty).

3. The ancient climate of the Central Plains.

According to the new achievements of geography and archaeology in recent ten years, we have a comprehensive and clear understanding of the ancient climate in China. There was a global warming period in the middle Holocene, which was roughly equivalent to the Yangshao cultural period in China, so it was also called "Yangshao Warm Period", which was 8000 ~ 3000 years ago.

The middle and lower reaches of the Yellow River (including the Huanghuaihai Plain) were in a warm and humid climate 5000 years ago. The remains of roe deer, bamboo rat, raccoon dog and other animals about 6000 years ago were found in Anbanpo site in Xi 'an. Now these animals mainly live in the Yangtze River valley, where the climate is warm and humid and swampy. At that time, there were some plants and animals found in subtropical areas in Beijing and Tianjin, mainly broad-leaved forests with oak and elm. According to the sporopollen research in Tianjin and Liaoning, there were water ferns in this area 7000 years ago, and there are also water ferns in Huaihe River basin today. A large number of warm-loving animals and bamboos were found in Neolithic sites in Henan and Shandong, south of Beijing and Tianjin. It is speculated that the annual average temperature in the Yellow River Basin at that time was about 2℃ higher than today. From 8000 to 2500 years ago, the broad-leaved forest in southern Liaoning was dominated by oak and alder, and the climate was warm and humid, similar to that in Shandong Peninsula today.

The results of sporopollen analysis of Neolithic sites in the Yangtze River valley show that the climate 5000 years ago was generally warmer and wetter than today. For example, the annual average temperature near Shanghai is about 2 ~ 3℃ higher than that in modern times, which is equivalent to the climate in central and southern Zhejiang today. Since the Middle Holocene, Taihu Lake has been in a hot, warm and humid climate. Elephants, rhinos and other animals living in tropical areas were found in the animal remains of Hemudu site in Yuyao, Zhejiang Province. The climate at that time was roughly close to that of Guangdong, southwest Guangxi and Yunnan in South China today. The average annual temperature in the Neolithic period in Hangzhou Bay was above 4℃ today. Others, such as around Dongting Lake in the middle reaches of the Yangtze River, Nanchang in Jiangxi and Anqing in the lower reaches of Anhui, have sporopollen analysis results, which prove that the climate was warmer 5000 years ago.

In short, from 10000 to 5000 years ago, it was in a warm climate period from Heilongjiang in the north to the vast eastern region south of the Yangtze River basin. The warm animals such as buffalo, elephant and tapir unearthed from Yin Ruins in Anyang, Henan Province can prove that this warm climate period generally lasted from BC 16 to BC 1 1 century Shang Dynasty.

In terms of vegetation, there were subtropical forests and swamp vegetation in the middle and lower reaches of the Yangtze River from 8000 to 5000 years ago. However, in ancient times, the Loess Plateau was not seriously damaged by vegetation as it is now. Before 2000, the eastern part of the Loess Plateau was covered with dense forests and bamboo forests, and there were still a large area of virgin forests in the Qinling Mountains. From Holocene to two or three thousand years ago, dense natural forest vegetation was also widely distributed in North China.

From 8,000 to 3,000 years ago, the climatic conditions in the Central Plains provided abundant resources for human survival and development, and were also conducive to primitive agricultural production. Finally, it laid the foundation for the huge population scale of the Central Plains.