Abstract: The ancient Juyan-Heicheng region is located at the lower reach of Ruo Shui River in western Inner Mongolia, and was a reclaimed area in Han, Western Xia(1032-1227A.D.) and Yuan Dynasties and now has alredy been desertified. According to the aerophoto analysis, the region at that time was a lower reach delta of Ruo Shui River with a fan shaped water system,which flowed eastward to the ancient Juyan Lake, The preserved farmlands, irrigational channels, residential centres, beacon towers etr. reflect that the farming areas had a considerable scale in the region during that period. With reference to the ages of unearthed artifacts and old buildings, the reclaimed areas in the region in Han Dynasty occupied the lower and middle parts of the delta; the reclaimed areas in the region in Western Xia and Yuan Dynasties occupied the upper and middle delta besides the old part of the reclaimed areas in Han Dynasty in the middle part of the delta. Heicheng, a main town in Western Xia and Yuan Dynasties was situated on north bank of east tributary of Donghe River in the middle and upper delta. The abandonment of Heicheng and the nearby reclaimed areas was related to wars at the end of Yuan Dynasty and the early of Ming Dynasty, to the destruction of water conservancy projects and to the cut-off of water sources. In Ming Dynasty, the areas in Hexi Corridor within the Great Wall was once again reclaimed on a large scale, the misuse of water resources in the upper and middle reaches also affected the water sources in the lower reach. Therefore, Heicheng has not been rejected since its abandonment.