After the border development, how to manage and consolidate the vast border areas and realize effective governance of the vast border areas?

Historically, the territory of the unified dynasty included not only agricultural areas, but also peripheral areas. This area is equivalent to the whole of Europe, and it is really large. However, the differences between the frontier and the mainland in economic model, ethnic composition and cultural tradition make the management of the frontier difficult.

For example, on the basis of the territory of the Qin Dynasty, the Han Empire not only consolidated the territory of the Qin Dynasty, but also made great progress in attacking the Xiongnu in the north, connecting the western regions in the west and comforting foreigners and Vietnam in the south. At its peak, its territory extended eastward to the central part of the Korean Peninsula, including all the Yunnan-Guizhou Plateau and a part of southwest Myanmar, and southward to central Vietnam, making it one of the largest dynasties in China's history. On this vast land, the northern frontier of the Han Empire extends northward from Hetao and Yinshan, including Lake Baikal, Altai Mountain and the place where the Huns lived to the west. The northeast frontier "starts from Lake Baikal in the west and reaches the Sea of Okhotsk in the east. China has ethnic groups, and the Heilongjiang and Wusuli river basins are all within the territory of China". The western frontier includes the whole northern Tianshan Mountains, southern Tianshan Mountains and Wusun and Kangju areas west of Tianshan Mountains. The southeast frontier extends from the East China Sea coast and the South China Sea to Hainan Island and Indochina Peninsula (now northern Vietnam); The southwest frontier includes most parts of southeastern Gansu, Qinghai, Sichuan, Yunnan and Guizhou and a part of Tibet. Among them, the main ethnic groups in the northern frontier are Xiongnu, Donghu and other ethnic groups, who live in both agricultural and pastoral areas and grassland areas; There are more than 30 countries in the western frontier that have settled in oases, and there are many "traveling countries" such as Bian and Qiang. The ethnic composition and economic forms of the northeast frontier are also diversified, including nomadic people such as Wuhuan, fishing and hunting people and farming people; Some of the "Baiyue" in the southeast frontier make a living by sailing and fishing, and some are engaged in settled farming; The ethnic composition of the southwest frontier is complex, living in groups and having dozens of monarchs. After the unification of the Central Plains, the Tang Dynasty established a more powerful unified empire by fighting against the Turks, unifying the western regions, managing the northeast, connecting with Tubo and assisting Nanzhao in the south. The territory of the prosperous Tang Dynasty greatly surpassed that of the Western Han Dynasty and became the largest and strongest feudal empire in the world at that time. The territory of the Tang Dynasty empire was naturally broader, the ethnic composition in the border areas was more complicated, and the economy and culture in the border areas were more diverse.