First, the natural and geographical factors that formed Chang 'an as an ancient capital.
In ancient China, as a country based on agriculture, natural and geographical conditions were always the first concern when choosing the capital. Among the physical and geographical elements where the capital is located, the choice of geographical location is very important. "Guanzi Riding" says: "All countries are based on mountains and must be above Guang Chuan." The ancient rulers often chose the capital as "above Guang Chuan" or "below the mountain" because they focused on controlling the whole country. From this perspective, Chang 'an is a place suitable for the ancient capital. Judging from the general geographical situation in China, it is generally high in the northwest and low in the southeast, so that Chang 'an's geographical position is relatively high, which has the taste of "overlooking" the Central Plains, so the ancients gave a high evaluation of Chang 'an, the capital city. For example, when commenting on Guan Zhong, he said, "The State of Qin won by form, and it was threatened by rivers and mountains, hanging thousands of miles apart, holding a million halberds, and Qin had 120." Convenient land, soldiers from the princes, like a strategically located building. ""your majesty's people are close to each other. Although Shandong is chaotic, Qin's hometown can be close to each other. Husband fights with others, does not pinch, does not pat on the back, and does not win. Today, your majesty's pressure on Qin's hometown is also a slap in the face to the world. "It can be seen that Chang 'an has the geographical conditions of being above Guang Chuan.
The condition of water resources is one of the main factors that must be considered in building the capital. In the Zhan Dynasty, people invariably chose cities close to rivers. This is because the area near the river has convenient transportation, rich water resources, fertile soil and rich products, which is suitable for primitive agricultural cultivation and is an ideal place for people to live. "Guanzi Riding Horse" says: "There is no need to use enough water near the high altitude drought, and there is no need to use water near the ditch to prevent the province. Because of natural materials, it has advantages. " In this sense, the location of the city must be high, but it must not be too far from the water source, and there must be enough water; On the other hand, the location of the city should not be too close to the water source, otherwise it will be vulnerable to water disasters, and it is necessary to build flood control facilities, which will consume a lot of manpower, material resources and financial resources. In terms of water resources, the ancient capital Chang 'an has very advantageous conditions. Volume 5 of Xi An Fu Zhi records: "The land of Chang 'an, Lian and Lu 'an pass through the south, followed by Jing and Wei Kui, Ba and Yan on the left, and Feng and Lu 'an on the right (that is, the waterlogged river). "In history, there is the name of' Eight Rivers Around Chang 'an'. These rivers flow through the east, west, south and north borders of Chang 'an, the capital city, respectively, and surround Chang 'an in the center, providing convenient conditions for Chang 'an's water use. During the Qin, Han, Sui and Tang Dynasties, the favorable conditions of "Eight Rivers Around Chang 'an" were fully utilized in the construction of Chang 'an City, and a number of artificial channels such as Longshou Canal, Yong 'an Canal, Qingming Canal, Caoqu Canal, Huang Qu and the canal crossing Chang 'an City were dug in a planned way from the east, south and west of the city, which not only solved the water problem of the capital in a planned way, but also further beautified the urban environment. From the climate point of view, although the climate in the historical period fluctuated from 400 to 800 years, the swing range of 1~20C ~ 20c basically did not affect the pattern of Chang 'an in warm temperate zone and temperate zone. Therefore, Chang 'an, located in the eastern monsoon region of Eurasia, is warm and humid in summer, with abundant rainfall and the same season of rain and heat, which is conducive to crop growth and human activities. Judging from the soil conditions, the loess and secondary loess in the upper part of Qinchuan were formed by the erosion and deposition of Weihe River and its tributaries, which have many advantages and are very fertile, laying a good foundation for the development of agriculture.
Second, the economic and geographical factors for Chang 'an to form an ancient capital
Economic and geographical factors are of great significance in the formation of the ancient capital. For ancient China, which was founded on agriculture, the advantages and disadvantages of economic geography must be considered when choosing the capital. In terms of economic and geographical conditions, Chang 'an has a mild climate, fertile soil and vast plains, creating superior natural and geographical conditions for agricultural production. At the same time, the construction of water conservancy in the past dynasties provided a guarantee for the agricultural economy here, which made the agricultural economy in Guanzhong area quite developed and was the richest area in the ancient world. Sima Qian said: "Guanzhong is sweating, harmonious with East China, and thousands of miles of fertile fields. I paid tribute from Yu Xia and thought I was going to other places. " "So Guanzhong land accounts for one-third of the world, with a population of no more than three, but it is a rich land, ranking sixth." In the Tang Dynasty, the soil in Guanzhong was still the most fertile in China. Book of the New Tang Dynasty (Volume 53) Records of Food Goods records: "Chang 'an, Tang Dou and Guanzhong are called Woye. "It can be seen that the agricultural economy in Chang 'an and its surrounding areas is very developed, which provides a solid material foundation for the formation of the ancient capital.
The richness of local products can also play an important role in the formation of the ancient capital. Because the number of products directly affects the development of industry and commerce. Guanzhong area is not only rich in soil, developed in irrigation and water conservancy, highly developed in agricultural economy and rich in products, but also located in the main road of east-west traffic, which is very conducive to the development of handicrafts and commerce. When talking about the foundation of the country in the Han Dynasty, he said: "Fu Guanzhong's left is faithful, and his right is Longshu, and fertile land is thousands of miles away. The south has the grace of Bashu, and the north has the benefit of being surrounded by tigers. Blocked on three sides, held fast, and the vassal was controlled on one side. The princes are stable, the rivers and rivers embrace the world, and the west gives the capital; The princes have changed, and it is enough to go downstream. This so-called golden city is thousands of miles away and is a land of abundance. " Yan Shigu noted, "Wealth is a mansion. It is said that the land in Guanzhong is rich in products and can be supported, so it is called Tianfu. " Dong Fangshuo hit the nail on the head: "The south of Fushan Mountain is blocked by the world, with Jianghuai in the south and Weihe River in the north. Its land is from east of Qianlong to west of Shangluo, and the soil is fertile. Hanxing, to the land of the Three Rivers, ends in the west of Bachan and the south of Jingwei. This so-called land of land and sea is also the reason why Qin captured Xirong and Shandong. Jade, gold, silver, copper, iron, jade seal, sandalwood, zhe, and imported goods cannot be confiscated. This is given by all the workers and printed by all the people. There are rice, pears, millet, mulberry, hemp, bamboo arrows, ginger and taro in the soil, and frog fish in the water, so that the poor can have food and have no worries about hunger and cold. Therefore, the number of picks is soil paste, and its mu is one gold. " When evaluating Guanzhong in Yuan Dynasty, Luo Tianxiang said: "Chang 'an is fertile and rich, surrounded by mountains and rivers, with the danger of the Red River outside, Hanzhong, Ba and Shu in the west, and the benefits of replacing horses in the north, so-called land of land and sea. "Such products, coupled with convenient transportation, have created very favorable conditions for the ancient capital Chang 'an to become a commercial metropolis and a handicraft center.
Third, the military geographical factors of Chang 'an forming the ancient capital.
When choosing the capital city, dynasties or regimes of past dynasties also attached great importance to military geographical factors and must consider geographical security. From the military geography of Guanzhong, Chang 'an has the advantage of "solid mountains and rivers". Surrounded by mountains on three sides, the Yellow River is in the east, and the mountains and rivers win narrowly. It is a place where you can attack and retreat. The southern part of Guanzhong area is the towering Qinling Mountains, starting from Baoji in the west and reaching Tongguan in the east. The west and north sides are composed of winding Beishan mountains, such as Longshan, Lushan, Qishan, Liangshan, Jiujun Mountain, Kue Mountain, Zijin Mountain, Yaoshan Mountain and Huanglong Mountain. It starts from Longxian County in the west, reaches the Yellow River in the east, and runs from northwest to northeast. Among these obstacles, there are Hanguguan, Tongguan, Linjin, Miguguan, Wuguan, Dasanguan, Longguan and Xiaoguan. It can really be said that "and one person keeps it, there is nothing to show." Therefore, "Qin, winning the country by shape, is dangerous to hinder rivers and mountains, hanging thousands of miles apart, holding a million halberds, and Qin wins 120." At the same time, Guanzhong area is the crossroads of east-west traffic. Relying on this, it can not only defend or organize the intrusion mainly from the nomadic aristocratic ruling groups in the northwest, thus shielding the agricultural areas in the middle and lower reaches of the Yellow River, but also commanding and controlling the Central Plains.
Through the discussion of the capital of Chang 'an, we can get the enlightenment that natural geography, economic geography and military geography are the basic conditions that dynasties or regimes must pay attention to when choosing the capital, and they have a very important influence on the choice of the capital. However, the location of the capital is not static, but changes with the changes of various social factors that restrict the capital. In a sense, the choice and relocation of the capital is caused by objective conditions, and it is a historical, humanistic and geographical phenomenon that is not transferred by human will.