Ming Great Wall Defense System

Timeline

1. c. 1372–1387Datong · Nine FrontiersAfter the Ming northern campaigns, earthen cities and fortified passes were built at Datong, Xuanfu, and elsewhere, with garrison stations established, integrating the remnant frontier walls of the late Yuan into a preliminary coherent northern defense line.
2. c. 1393–1400Gubeikou · Ji-LiaoFrom the late Hongwu period through the Jianwen years, the Ming court added brick-and-stone walls and built hollow watchtowers and beacon towers in the Ji-Liao and Xuan-Da defense zones, strengthening early warning and interception at the northern gate of the capital region, forming a border defense network complementing the garrison military system.
3. c. 1410–1424Jiayu Pass · Nine FrontiersThe Yongle reign continued extending the defense line westward, consolidating the passes of the Hexi Corridor, so that the western and eastern sections of the Ming Great Wall mutually supported each other strategically, establishing the pattern of the Nine Frontier Garrisons.