Parallel mountain ranges extend from the Daen Lao Range (ทิวเขาแดนลาว), in the southern region of the Shan Hills, in a north-south direction, the Dawna Range (ทิวเขาดอยมอนกุจู) forming the western border of Thailand between Mae Hong Son and the Salween River. To the east the Thanon Thong Chai Range (เทือกเขาถนนธงชัย), the Khun Tan Range (ทิวเขาขุนตาน), the Phi Pan Nam Range (ทิวเขาผีปันน้ำ), as well as the western part of the Luang Prabang Range (ทิวเขาหลวงพระบาง), form the natural region of the Thai highlands together with the former.