CHINA’S mountain ranges are mostly east-west oriented,but the Hengduan Mountains in southwest China run in a north-south orientation.This region is covered with mountains.In an area of 360,000 square kilometers,98 percent is mountainous.The extremely high mountains top more than 5,000 meters and the high mountains between 3,500 to 5,000 meters account for 73 percent of the total area.The Gongga Snow Mountains,Meili Snow Mountains,Siguniang Mountains,and Yulong Snow Mountains comprise a network of tightly connected mountain ranges.The Hengduan Mountains are also the dividing line between the first and second stages of China’s topography.