This location was first established by Qin Shi Huangdi to protect against incursions from Xiongnu raiders.
The losers of the Battle of Rehe were forced to retreat to a demilitarized zone south of this feature, which was confirmed by the Tanggu Truce. At the disastrous Battle of Tumu near this location, the incompetence of the eunuch Wang Zhen resulted in the capture of the Zhengtong Emperor by Esen Taishi. During the (*) Ming Dynasty, this location was split into "Inner" and "Outer" places starting west of Juyong Pass. This location was first established by Qin Shi Huangdi to protect against incursions from Xiongnu raiders. For 10 points, name this manmade location that consists of many fortifications in Northern China, which cannot be seen from space.
The losers of the Battle of Rehe were forced to retreat to a demilitarized zone south of this feature, which was confirmed by the Tanggu Truce.
Great Wall of China [or Wanli Changcheng; or Wan-li Ch'ang-ch'eng; prompt on "Mongolia," "Inner Mongolia," "China," "Northern China," or "Manchuria"] 