What is the significance of security change?

As an important strategic measure of "border protection", the development of frontier reclamation is of great significance to the stability and development of frontier areas in past dynasties. On the one hand, while completing the task of guarding the border, the border guards participate in reclamation, ploughing on the spot, and are self-sufficient, which can not only ensure the supply of rations to a certain extent, but also save or reduce the burden brought to the people by long-distance transportation, which is helpful to realize "supporting the border with the border". On the other hand, with the development of reclamation, the social economy of the frontier has been developed and the military reserve horses have been growing, which has enabled the dynasties to improve their comprehensive defense capabilities and maintain their military presence in the frontier on the premise of solving the livelihood of frontier officers and soldiers, thus making the frontier a reliable strategic barrier for the Central Plains and playing a certain role in defending and fighting the southward migration of nomadic people. As Zhao Chongguo said, "Reclaiming land from the sea has both the benefits of death and the benefits of defense." At the same time, because the location of the wasteland is concentrated in frontier fortress, strategic location and traffic hub, the settlers are also an integration of soldiers and civilians, far and near, corresponding to each other. "Farming in time, proper training, fighting in case of enemy, and ploughing in case of enemy's going" enables them to fight anytime and anywhere, independent of rear supply, and integrates economic benefits and military value. Therefore, as an integral part of border military deployment, border towns have gradually become military and economic. Therefore, the strategy of opening up wasteland in the frontier has been valued and affirmed by far-sighted politicians in past dynasties. For example, Cao Cao attributed Emperor Wu of Han Dynasty's acquisition of the Western Regions to the success of cultivating the western regions, and thought that "filial piety cultivated the western regions" fully affirmed the national defense value of cultivating the western regions in Han Dynasty. In the Southern Song Dynasty, when Lv Zuqian reflected on the national defense policy of "refusing to defend the land against the enemy, defending the weak inside and the weak outside" in the Song Dynasty, he especially praised the policy of reclaiming land in the Han and Tang Dynasties, believing that it was a "good defense" move of "defending the land from the outside". It can be seen that the frontier reclamation work, characterized by the combination of military and civilian, peacetime and wartime, and the combination of military and agricultural, has important strategic significance for consolidating the frontier defense and maintaining the long-term stability of the frontier, thus becoming an important strategy and effective method for managing the frontier in past dynasties.

Another strategic measure to strengthen border defense is "moving to the real border". In history, nomadic people in the north have irregular movements, are good at riding and shooting, and have strong military advantages. Their attack on the frontier was extremely sudden. As Chao Cuo said, "The livelihood of the Hu people is out of reach and it is easy to disturb the frontier." Therefore, the central plains dynasty was at a disadvantage in defending against the harassment of nomadic people, which can be said to be impossible to prevent. As long as one place is broken, it is thousands of miles away. Therefore, it is difficult to achieve the ideal effect simply by taking military preventive measures. Meanwhile; Because the frontier is far from the mainland, it is neither practical nor practical to station a large number of troops, and once something happens to the frontier. Thousands of miles to help, less is not enough to resist, more is a waste of money, and the country has a heavy burden. Chao Cuo analyzed in his "Supporting the People and Relying on Sparseness" that it is not the way to rely solely on the central government to send troops to defend against the Huns. Constantly recruiting grain, grass and soldiers, corvees and taking turns to guard the border will only make the country overwhelmed, the people restless, the defense is difficult to work, and the border crisis cannot be truly solved. 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 great strategic significance to move the residents of the Central Plains to live and live in the border areas in a planned way, which will strengthen the border defense and stabilize the border areas.

In terms of economic layout, the Central Plains, represented by the East in history, developed earlier, with dense population and narrow land. 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 strategic move with multiple objectives. Sang Hongyang said, "Let's relax China and adjust the border. If the border is strong, then China will be safe, China will be safe, and nothing will happen. " Wang Fu of the Eastern Han Dynasty also said when discussing the feasibility and necessity of immigration border consolidation: "The first king legislated and was pragmatic, and built it together with China." "Today, the county is thousands of miles away, and there are two counties in each place, and the family is rich by hundreds. However, when Taishou returned to Wan Li, it was inaccessible, and the fertile land was abandoned and not developed. " On the contrary, "Zhongzhou County, the land expansion, can not be born, and the household registration is one million, and the fields are complete." 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".

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. It was through the strategic measures of emigrating to Guanzhong and Northwest China that the Western Han Empire coordinated the economic center and the political center. On the one hand, it defended the political center of the empire, on the other hand, the border counties close to the political center became reliable strategic bases for operating the northern and northwest frontiers. On the contrary, the Eastern Han Dynasty, with Luoyang as its capital, did not focus on Guanzhong and Longyou. In this way, the desolation of border counties directly affected the security of the eastern Han border, and it was difficult for the eastern Han dynasty to make great achievements in border management.

All the unified dynasties in history paid special attention to the work of "immigration to the real border", and regarded it as a long-term plan and strategic measure to "strengthen and stabilize the border", which was incorporated into the big system of border management and implemented by the government in a balanced way. This is manifested in the following aspects: First, the immigration location is selected at the strategic forefront. For example, the Western Han Dynasty once migrated from Huanghuai Plain to northern Shaanxi, Longyou and Hetao on a large scale to enrich Guanzhong and border counties. The second is to formulate various supporting preferential policies to ensure the actual effect of immigration to the frontier. For example, the Tang government stipulates that the local government in the origin of immigrants must provide clothes, cattle, rations, seeds, daily necessities and low-interest loans to recruited immigrants (children of ethnic minorities and Han nationality) to help them settle down; Officials recruited craftsmen from all over the country to accompany the immigrants to the resettlement sites, so that they could make weapons and farm tools in military cities to serve the immigrants; After the immigrants settle down, there is still surplus grain besides self-sufficiency. The state should buy and reward reclamation at double price and do everything possible to support small farmers in the border areas. The third is to strengthen the organization and management of immigration work. The government selects competent grass-roots officials, organizes immigrant production, establishes a perfect organization under the jurisdiction of the village administration system, popularizes the Central Plains system in frontier immigrant areas, and constantly turns the frontier into the mainland. The fourth is to organize immigrants to conduct military training. "Choose their talents and have guardians, learn the terrain and know the people's hearts, live in the country and learn the law, and teach the people to meet them. Therefore, if you are a pawn, you must be strong outside and hollow inside. Get used to it and don't let it migrate. " That is, using the resettlement psychology of immigrants after settlement, perfecting civil defense organizations, conducting appropriate military training and consolidating border defense.