Pakistan is divided into three major geographic areas: the northern highlands; the Indus River plain, with two major subdivisions corresponding roughly to the provinces of Punjab and Sindh; and the Balochistan Plateau. Some geographers designate additional major regions. For example, the mountain ranges along the western border with Afghanistan are sometimes described separately from the Balochistan Plateau, and on the eastern border with India, south of the Sutlej River, the Thar Desert may be considered separately from the Indus Plain. Nevertheless, the country may conveniently be visualized in general terms as divided in three by an imaginary line drawn eastward from the Khyber Pass and another drawn southwest from Islamabad down the middle of the country. Roughly, then, the northern highlands are north of the imaginary east-west line; the Balochistan Plateau is to the west of the imaginary southwest line; and the Indus Plain lies to the east of that line.