Treatise on Military Preparedness, Volume 90

[This garrison extends for] over one thousand li A li is a traditional Chinese unit of distance, roughly 500 meters or one-third of a mile.. Outside the garrison reside the subject barbarians of the Three Guards of Doyan; to the northeast are the Chahar Mongols; and to the northwest, the tribes of Qingbadur, Dazizhi, Gantu, and others dwell and graze their herds.

According to the records, the passes of:
Shanhai, Shimen, Yanhe, Jianchang, Taiping, Xifeng, Songpeng, Malan, Qiang-
-zi, Caojia, Gubei, Shitang, Huangkou, Damao, Yiyuan, Jieling, Qingshan, Taolin,
Lengkou, Chaya, Yuling, Dongjiakou, Lijia Valley, Panjiakou, Hongshan, Luowen-
-yu, Da’ankou, Kuandian, Huangya, Jiangjun, Shizhen, Luguan, Jijia Village, Heigu-
-guan, Simatai, Chaohe River, Baima Pass, and Dashui Valley—all are extremely strategic and vulnerable points.
The term "strategic and vulnerable" (original: chong 衝) refers to locations where enemy cavalry could most easily penetrate the frontier, requiring the highest level of military preparedness.

In the language of the Northern Nomadsoriginal: fan 番, a general term for non-Han peoples., places such as Daning are called Uriang original: Wuliang 兀良, referring to the Uriankhai tribes.. Slightly south of the Ordos Loop original: Hetao 河套, the great bend of the Yellow River. is Aomulin; slightly north is Laomulin, located five or six hundred li from the Ji border. In this region, the Eastern Nomads and the Tuman tribes reside and graze.
original: Tuman 土蠻. This refers to the Tumen Jasagtu Khan of the Mongols, a major leader who posed a significant threat to the Ming borders in the late 16th century.