How did the dynasties strengthen border defense?

Another creative strategic measure to strengthen border defense in past dynasties is "immigration to stabilize the border".

The Necessity and Feasibility of Implementing "Immigrant Reality"

China's strategy of "moving people to the real border" in past dynasties is not only a creative move based on the traditional concept of border management, but also has its own difficulties.

On the one hand, although the frontier is far away from the hinterland of the empire, sparsely populated and economically backward, according to the traditional world view, these "edges" are undoubtedly an indispensable part of the whole "world". Therefore, "moving the population to the real border" is undoubtedly "dominating the country"-multiplying the border population, strengthening the development of the border areas and promoting the social and economic development of the border areas.

On the other hand, the frontier has a very important strategic significance in national defense and is an important shield of national defense. To protect the security and stability of the hinterland of the imperial center, we must first mobilize troops from the mainland to defend the frontier. However, in order to maintain a sufficient number of border guards in the frontier, it is not only necessary to change the guards regularly, but also costly, and it is necessary to transport a large amount of food from the mainland. At the same time, because the frontier is far away from the mainland, a large number of troops are neither practical nor practical. Once something happens in the frontier, it is not enough to help thousands of miles to resist the attackers. On the contrary, it will waste people and money and the country will bear a heavy burden. Chao Cuo analyzed in "Taking the People for Migration" that it is not the way to rely solely on the central government to send troops to defend against the Huns. Constantly levying grain and conscription, levying corvees, and guarding the border in turn will only make the country overwhelmed, the people restless, the defense difficult to work, and the border crisis cannot be truly solved. Therefore, it is difficult for the Central Plains Dynasty to achieve ideal results only by relying on border guards for simple military defense. In addition, the garrison troops have limited time in the frontier and are "chess pieces in the distance." They don't know the local ethnic customs, nor are they familiar with the geographical environment and situation in the border areas. Moreover, they will miss their hometown for many years, and it is difficult to fully undertake the task of defending the frontier. And "moving to the real border", that is, moving to the border before and after military conquest, can not only provide material guarantee for military operations, but also move to idle places on a large scale after repelling the invasion and consolidate the existing achievements of military conquest. Therefore, it is of strategic significance to move the residents of the Central Plains to the border areas in a planned way, so that there are many residents in the border areas. Only by building cities, houses and villages can we fix the frontier forces and integrate the frontier soldiers and civilians.

In addition, as far as the geostrategic situation is concerned, "the scenes of China's ancient history activities are mainly in the Yellow River Basin, with the forces in the upper reaches of the west dominating and the cultural economy in the lower reaches of the east dominating". For example, when the Western Han Dynasty made Guanzhong its capital in history, "Chang 'an was the first in the country, and the culture and economy of the East were continuously transported to the west, blending with the western forces, and then extending from Chang 'an to the northwest, such as expelling the Huns and opening up the western regions. The posture of establishing a country in the Western Han Dynasty is often coordinated, dynamic and enterprising. Therefore, by emigrating to Guanzhong, Northwest China and North China, the economic center and political center of the whole country can be coordinated, which not only protects the political center of the empire, but also helps to build border counties close to the political center into strategic bases for border management. On the contrary, if the frontier counties are barren and dilapidated, it will not only directly affect the security of the frontier, but also affect the stability of the political center. For example, in the Eastern Han Dynasty, because the capital was in Luoyang, it did not focus on Guanzhong and Longyou, so it was relatively passive in defending the "barbarians". Cai Yong in the Eastern Han Dynasty analyzed in "Chen Zhenggui in Shang Feng Shi": "You Zhou rode suddenly, Jizhou was a strong crossbow, and he was a good soldier in the world. If something is going on in four directions, he must bring it to the second state. Years of famine, food prices range from one to six or seven hundred. So, Yu Xia, a captain of Wuhuan, went to Xianbei and returned in vain. The island was killed and injured, and Gong Bing was completely destroyed. "It can be seen that it is difficult for the Eastern Han Dynasty to make great achievements in border management, and the desolation of border counties is undoubtedly an important reason.

In terms of economic layout, the eastern part, represented by the middle and lower reaches of the Yellow River, was developed earlier in history, with narrow land and dense population, while the border areas were vast and sparsely populated, and the labor force was scarce, so even areas suitable for farming were not developed, which was very unfavorable to the stability of the border areas and the long-term stability of the country. Cui Sai, a political commentator in the Eastern Han Dynasty, said in On Politics: "In ancient times, the people of Qing, Xu, Yan and Ji were thick and narrow, and they did not give in to each other. However, Sanfu County and the nearby counties of Liangyou and Youzhou are sparsely populated and do not cultivate. People moved to other places, hungry or not, and the sheep still had to be raised and disposed of by the owner. If the grass is lush, it is rich and fertile; If you put it in marinade, you will consume less. " Therefore, emigrating from the economically and culturally developed middle and lower reaches of the Yellow River to the border areas not only conforms to the law of economic development, but also promotes the development of the border areas and enhances the comprehensive strength of the country, which is a good thing for multiple purposes. In this regard, politicians of all ages have a clearer understanding. For example, Sang Hongyang clearly pointed out: "If China is fat, it is necessary to adjust the border. If the border is strong, then China will be safe, China will be safe, and nothing will happen. " When discussing the feasibility and necessity of "migrating people to the real border", Wang Fu of the Eastern Han Dynasty also said: "It is also pragmatic to legislate before the king to build a China." "Today, thousands of miles away, there are two counties in each county, with hundreds of families, but the prefect returned to Wan Li for a week and there were no people, so the fertile land was abandoned and not developed." On the contrary, "Zhongzhou County, with its territorial expansion, can't make a living, but it has a household registration of one million and complete land. There is no room for people. Therefore, immigration to border counties conforms to the economic law of "those who are empty make up for it, those who are real make up for it", and it is really the key to China's security to "share weal and woe, share weal and woe, and fill the border".

For various reasons, spontaneous migration activities are also common in history. For example, at the turn of the Song Dynasty at the end of the Han Dynasty and the Song Dynasty at the end of the Tang Dynasty, due to the war in the Central Plains, a large number of Han people moved south or moved to other border areas. Although the role of these immigration activities is undeniable, they are not government actions, lack of overall planning and are difficult to sustain. Because as long as it is not natural or man-made disasters or other inevitable reasons, under normal circumstances, mainlanders are rarely willing to abandon their homes and leave their homes for frontier areas with unfamiliar living and interpersonal environment. Of course, the objective reason is that the economic model of small-scale peasant economy can rarely withstand this kind of tossing. As Zhong Changtong pointed out in Long Talk about Profit and Loss: "There are ten acres of mulberry in summer and barren fields in Yuanzhou. Secular security, if you die, you won't make it. Who can go by himself? " Therefore, after the reunification of the country, it has become an important strategy of the central government to formulate the border development strategy and mobilize the mainland people to engage in production, settlement and life in the border areas by relying on administrative resources.