The Han dynasty wooden slips found in Juyan prove that the term jiangluo as recordedin The Book of Han does not mean the death and falling of trees, as commented by Yan Shigu, but was rather a kind of barrier built by logs in the Han dynasty. As a form of frontier barrier connecting lit beacons, the jiangluo recorded by these wooden slips is described as being about 3 meters wide at the bottom and 2 meters wide at the top with a height of approximately 3 meters; the total length varied greatly, sometimes reaching as long as several thousand meters.This form of barrier is significantly different from tiantian, huluo, and yangmaqiang(near barrier walls), but similar to the construction of "bo" recorded in Mo-Tse, and only gradually became frontier barrier walls connecting beacons. Sites of jiangluo construction can today be found in the Juyan region.
