On the Road to Anxi

As one drives from Dunhuang to Anxi, ruins of several watchtowers can be seen along the way.   Clearly all along the flanks of the mountains just to the south of the valley was a defensive line, to protect against incursions through the stream valleys that descended to the plain.  One of the better preserved of these fortifications is located precisely at the point where a significant stream enters the main valley.  In addition to the very substantial watch tower, there is a fortified building, which presumably was the residence of the garrison.