As a major strategic move to "Anbian", what does "Tuntian" mean?

The essence of garrisoning is to select some places suitable for the development of agricultural production in border areas, and let the border garrison include combat troops, garrison soldiers, and field soldiers to cultivate and garrison for farming and fighting. Historically, after the Han, Tang, and Qing Dynasties unified their frontiers, they all implemented farming as a basic national policy to protect and stabilize the frontiers for a long time. For example, before and after the conquest of Dayuan, Emperor Wu of the Han Dynasty adopted the suggestions of Sang Hongyang and others to organize farming in the Luntai and Quli areas (today's west of Yuli, Xinjiang), and established military envoys and military commanders to organize and manage the land. A large number of field soldiers and soldiers settled in the Western Regions, not only cultivating thousands of hectares of fertile land, providing material support for border guards, providing security protection for Han envoys coming and going, and curbing the power of the Huns. In order to solve the problem of food supply for the troops stationed on the border, the Tang Dynasty also opened large-scale farming. "Wherever the border guards were guarding and transport was not provided, farming was set up to benefit the army's reserves. ... All the military prefectures in the world managed the farming, totaling 990 There are two”. Its farming organization was complete, its territory was vast, and its scale was far greater than that of the Han Dynasty. In the Qing Dynasty, the Manchu rulers paid more attention to promoting farming, setting up ranches, and developing mining in border areas such as Mongolia and Xinjiang from the perspective of "building the Great Wall."