Gansu

Gansu was the westernmost of the Nine Garrisons, anchoring the defense of the Silk Road corridor and the Jiayu Pass.

Ji Garrison

The Ji Garrison (Jizhen) was the military district responsible for the Great Wall sectors directly north and northeast of Beijing. It was considered the most vital of the frontier commands because of its proximity to the Emperor.

The Study of the Bureau of Geography states:
original: "Zhifang Kao" (職方考). This refers to the administrative and geographical records maintained by the Ministry of War.

The Ji Garrison serves as the left flank of the Capital. At the beginning of the dynasty, the Xuanfu and Liaodongoriginal: "Xuan-Liao" (宣遼). These were the two garrisons flanking Ji to the west and east, respectively. garrisons were interconnected like the legs of a tripod. The "Three Passes" of the Ji region were originally considered internal territory. However, since the administrative seat of DaningDaning was a strategic military outpost in modern-day Inner Mongolia that was abandoned and moved inland early in the Ming Dynasty, creating a defensive vacuum. was moved inward, the Three Guardsoriginal: "San Wei" (三衛). This refers to the Uriankhai Mongol tribes—Doyan, Tai'nin, and Fuyu—who occupied the lands north of the Ji Garrison. have circled and loitered nearby; consequently, the region became a direct neighbor to the Northern Nomadsoriginal: "Lu" (虜). A historical term used by the Ming to refer to Mongol groups..

The Ji Garrison is divided into twelve routes, governed by three wings.
To the east, it borders the Liaodongoriginal: "Liao-zuo" (遼左). Literally "Left of the Liao River," referring to the Liaodong Peninsula region. region, where defense must be maintained by both land and sea.
In the center, numerous mountain passes are established; the duties of pacifying the tribes and distributing imperial rewards are very frequent here.
To the west, it internally shields the regions of Changping and Yongping, while externally it controls the Great Wall.
This sector includes the Chao River and the Gubei Passoriginal: "Gubeikou" (古北口). One of the most famous and strategic passes of the Great Wall, leading directly toward Beijing..

Since the Gengxu Incidentoriginal: "Gengxu" (庚戌). This refers to the year 1550, when the Mongol leader Altan Khan bypassed the border defenses and laid siege to the suburbs of Beijing, prompting a massive overhaul of the city's defenses., a Supreme Commander has been specifically appointed to be stationed at Miyun to coordinate and control the region alongside the local Governor and General-in-Chief. In recent years, the repair of fortifications and the training of guards have been gradually completed. Troops from both the north and the south are trained together; thus, the defenses can truly be described as secure.

The border of this garrison begins at Shanhai Pass in the east and extends to Dashuigou in the west, where it reaches the boundary of Mutianyu in the Changping Garrison. The total length of the border is...