Abstract: The region discussed in this article is within the realm of the southern fringe of the Taklamakan Desert. It is situated along the ancient Silk Road between Khotan and Ruo-chiang. This article was written on the basis of field investigations and analysis of historical materials.The theme includes three problems.(1) Whether or not a river existed along the southern fringe of the Taklamakan Desert in the historical period? It was recorded in "Shui-jingju" (A Commentary on ancient river system) that there was a river called"Nan ho" (south river) flowing from Khotan eastward along the southern fringe of the Taklamakan Desert and pouring into the "Lou-Lan Sea" (now Lop-Nor).This concerns an important problem about historical geography, that is, Whether or not the river system of this region had experienced a fundamental change.After analysing many historical materials and modern geographical works, we find that no Nan-ho existed there throughout historical poriod.(2) Did the number of Oasis between Khotan and Ruo-Chiang gradually increase or reduce throughout historical period? Since it reflects whether the struggle of man against desertification succeeded or failed it is an important problem too.After comparing several records in historical books from Han to ching dynasty, we find that the mumber of Oasis has increased gradually period by period.(3) East of Khotan several settlements and towns had been abolished, and the main road had been shifted too. What were the causes behind these phenomena? For solving the problems, the ruins of Andere, Niya and old Cherchen were selected and discussed in this article.