Known as the "Roof of the World,"the imposing Qinghai-Tibet Plateau is the highest plateau in the world. As a unique geological phenomenon in East Asica, the Qinghai-Tibet Plateau stands, along with the east monsoon area and northwest arid area, as one of the three distinctive natural regions in China, and has exerted a great influence upon the formation and developnment of the geographical landcape in adjacent areas. With vast territory and high and steep terrain Tibet Autonomous Region forms the main part of the Qinghai-Tibet Plateau, covering 26.52 to 36.32 degrees north latitude and 78.24 to 99.01 degrees east longitude. This extensive region has been called the Tibet Plateau, "a plateau on the Plateau." In fact, Tibet Autonomous Region also includes areas with a relatively low elevation on the southern edge of the Qing hai-Tibet Plateau.