How did the dynasties govern the frontier?

For a unified empire, the biggest difficulty in consolidating and governing the vast frontier lies in the huge differences in cross-border production methods and economic methods. Because of the difference of natural environment and the resulting difference of production mode, it will inevitably lead to the difference of industry between Han nationality and frontier ethnic minorities, and lead to their differences in lifestyle and culture. As the Book of Rites said, Wang said, "The people of China who are willing to tolerate foreigners are all natural and cannot be changed. There are tattooed barbarians in the East, and there are also people who don't eat with fire. In the south, it looks good, and some people don't eat with fire. The west is arrogant and stands in clothes, and some people don't eat; There are clothes and feathers caves in the north, and there are people who don't eat grains. " The so-called "food without fire" means no cooked food. According to the explanation of Zheng Xuan, a Han Chinese, it is obviously a natural gathering life in the hot and humid places in the south. "No food" means no food, which belongs to the economic life of hunting and animal husbandry in the cold areas in the north. In the historical records, Sima Qian also noticed the differences in economic models of various ethnic groups in the border areas, and specifically listed five biographies of ethnic history. Among them, Biography of Xiongnu not only describes the characteristics of Xiongnu's herding and hunting life and its combination with the military, but also pays special attention to its daily life, marriage system and cultural level. In the Biography of Southwest China, Sima Qian divided the ethnic minorities in this area into several different types according to the different modes of production. It can be seen that the differences in economic model and lifestyle between the border region and the Central Plains exist objectively, and the promotion of agricultural economy is the key to consolidate the border region.

The feudal dynasty of China really consolidated and stabilized the frontier with the progress of agricultural economy as the forerunner and foundation. Since the pre-Qin period, the mode of production of residents in the middle and lower reaches of the Yellow River has gradually differentiated. Huaxia nationality, the predecessor of the Han nationality, first developed from hunting and gathering culture to farming culture because the soil and climate in the residential area were more suitable for the development of primitive agriculture and easier to explore, and then continued to develop into areas suitable for farming, but tribes with nomadic fishing and hunting as the main economic mode and production mode were busy. Roughly from the middle and late Warring States period, the economic pattern in the Central Plains changed from farming-based animal husbandry and forest and fishing to a single farming pattern, and farming became the only industry to maintain social stability, while the "Four Suits" was "grazing livestock and shooting for a living". In the competition between the two economic types, farming culture takes the initiative and advantage because of its stronger economic strength and adaptability. Tribes mainly engaged in animal husbandry retreat to the surrounding areas such as northwest and north, and farming culture and animal husbandry culture are increasingly isolated in geographical space.

However, in the pattern of "China people and foreigners", it is not unlimited for the unified dynasty to promote agriculture to the vast border areas. Due to geographical and climatic reasons, the economic forms of various places have their rationality of existence. Ban Gu said: "The barbarian people are greedy for profit, left-handed, and have a human face and a beast's heart. They are different from China, with different customs, different diets and unreasonable speech. They live in the cold and dew land in the north, chasing grass and shooting for a living by livestock, separated by valleys and sand curtains, so heaven and earth are a must. Moreover, the agricultural civilization in the Central Plains encountered different situations in the process of advancing to the frontier. In areas suitable for agricultural economy, such as oasis areas in the south, northeast and northwest, and agricultural and pastoral areas in the north, agricultural economy is easier to move forward because it can better adapt to local natural and social conditions and meet the needs of dense and growing population. China culture also shows strong assimilation, such as from Chuzhuang Tuqiao to Qin, Han and Wu Dynasties, Tang Zong Song Zu and Yuan, Ming and Qing Dynasties, pointing to the south with soldiers, and even sweeping the south without using force. At the same time, with the turmoil at the end of the Han Dynasty, Yongjia Southcrossing, Anshi Rebellion, disputes at the end of the Tang Dynasty, the Five Dynasties and Ten Kingdoms, and Jingkang Southcrossing, several large-scale immigrants moved southward, and the agricultural economy was promoted from the Yellow River basin to the Yangtze River and Pearl River basins. Except for some remote valleys, "Nan Man" and "Xi Rong" in the pre-Qin period were basically merged into China and no longer existed. On the other hand, when nomads enter the Central Plains and arrive in the Central Plains suitable for agriculture, they are often forced to abandon the original nomadic economic model and adopt an agricultural economic model with higher production efficiency, and gradually integrate into the China family. For example, after the Qin and Han Dynasties, due to the war in the Central Plains, nomadic people relied on strong force to move inward several times and even entered the Central Plains. Some nomadic rulers stubbornly maintain nomadic habits and think that "Han people can't help the country, but grazing is also empty." "Therefore, it is not successful to promote nomadic or animal husbandry production methods in the Central Plains represented by the middle and lower reaches of the Yellow River. During the Wei, Jin, Southern and Northern Dynasties, the middle and lower reaches of the Yellow River were at war for a long time and the population dropped sharply. " Bones are exposed in the wild, and there are no crows in a thousand miles. "Nomads turned a large number of abandoned farmland into pastures, once grazing was realized, but once the society was stable, the economy recovered and the population increased. Then it quickly returned to the mode of production based on agriculture, and finally all those who entered the Central Plains were sinicized without exception. Historically, the reform of the localization of Emperor Xiaowen in the Northern Wei Dynasty and the necessity for the rulers of the Qing Dynasty to abolish "enclosure for grazing" are all evidences.

In contrast, the northward expansion of agricultural economy is relatively slow. The vast mountain plateau in the famous "crescent zone" belongs to the transitional zone of semi-agriculture and semi-grazing. If the economic model of these areas is mainly determined by the strength comparison between Hu and Han, then the efforts of the Central Plains Dynasty to promote agriculture in the area north of the traditional dividing line between agriculture and animal husbandry often fail. The vast frontier, especially the vast grassland and desert areas in the north and west, is a superior production environment for nomadic people to roam freely, and nomadic economy still has its vitality in these areas. Therefore, it is the most suitable mode of production for nomadic people to operate nomadic industry in the north of the Great Wall through natural selection. On the contrary, the Han people can't adapt to the climate in the cold zone, and the efficiency of agricultural production is very low, so they can't give full play to the advantages of farming economy. Even if some rulers once promoted the Central Plains economic model in these border areas with military victory, it was often unsustainable. The Han people who moved to these areas did not sinicize each other, but gradually became infected with Hu Feng, "living on weeds, eating meat and drinking cheese" and living a nomadic life. In history, Qin Shihuang's Hanwu attacked the Huns, levied Wu Huan, and Emperor Taizong destroyed the Turks. Although they take the initiative to defend themselves, they don't want to get their land, but "getting their land but not farming" is also an objective constraint. For example, from the Qin Dynasty to the Western Han Dynasty, after the Huns were exiled, immigrants settled in the northern and northwestern border counties, which greatly promoted the farming economy and extended to the foot of Yinshan Mountain, making the buildings south of Qin Changcheng once connected, and the villages were opposite. Among them, "Henan Land" was even called "New Qin", comparable to Qinchuan in Guanzhong, but it had to be evacuated voluntarily soon. After the Eastern Han Dynasty, nomadic life resumed in these areas.

It can be seen that the promotion of agricultural economy to the border region can not be completed by force. The unified dynasty based on agriculture had to yield to the "natural law", admit the objective reality that agricultural economy and nomadic economy coexist in different regions, and adopt different management strategies for the vast frontier areas with different economic forms.

Secondly, the culture in the border areas is unique. Generally speaking, ethnic religions and foreign religions have a greater influence on border areas. For example, Buddhism in the Central Plains experienced hundreds of years from Han Wei to Sui and Tang Dynasties in China, and became a tool for feudal rulers to "educate by Shinto". However, due to the backward culture, most of the frontier areas absorbed foreign religions and combined with the original superstitions, which turned out to be a factor deviating from China culture. As a vent of dissatisfaction with the government, folk religion, after being squeezed in the Central Plains, often looks for activity space in the border areas with weak Confucian cultural traditions.

In addition, the frontier is often the fault area of Chinese culture or the intersection area of various civilizations, and centrifugal force and centripetal force coexist. For example, the western region to the west of Hexi Corridor is at the crossroads where various civilizations meet, and the proximity of foreign culture and nomadic culture makes the western region dissociate from the jurisdiction of the Central Plains dynasty from time to time. Historically, in the oasis areas such as Kuqa and Yanqi in the western region, the influence of Indo-European civilization was once remarkable, which rebelled against the Central Plains, affected the stability of the western region as a frontier of China, and even the separatist activities of "East Turkistan" appeared in the 1940s. Of course, there are also factors such as the weakness of the central government, but the special situation of the western region at the intersection of several major civilizations makes it difficult for the Central Plains dynasty to operate this region by force alone, and it is necessary to carry forward Chinese culture represented by farming civilization. Another example is the six towns in Hebei during the Northern Wei, Sui and Tang Dynasties, as well as the "Anshi Rebellion" and the separatist regime in the buffer regions. Although there are political reasons, as a frontier area, the long-standing "Hu Hua" here cannot be ignored.

It can be seen that the objective gap between the vast border areas and the mainland in politics, economy, society and culture makes different border areas present different regional characteristics, and also makes various contradictions in the process of border management complicated, with serious unstable factors, security risks, crises and centrifugal tendencies, which seriously affects the unified political pattern. Therefore, it is still a very complicated and arduous task to stabilize and consolidate the vast border areas with complex ethnic composition, different economic forms and different cultural traditions, defend the border areas and maintain a unified political order, and it is also a major practical issue faced by unified dynasties in past dynasties.