Tibet is an autonomous region situated on the Qinghai-Tibet plateau in the southwest region of China. It is bordered to the north by Xinjiang Uygur autonomous region and Qinghai Province, to the east by Sichuan Province, to the southeast by Yunnan Province, and to the west and south by Nepal, Sikkim, Bhutan, India, and Myanmar. The total area of Tibet is about 1.2 million square kilometers or 12.8% of the overall land mass of China. Situated over 4000 meters (13000 feet) above sea level, Tibet is made up of a rich and varied topography that can be split into three distinct geographic sections: the west, the south, and the east. The western section also referred to as the North Tibet Plateau, lies between a line joining Kunlun Mountain and Kangdese Mountain, and one joining Tonglha Mountain and Nyainqentanglha Mountain and constitutes two-thirds of the total area of Tibet. The southern section of Tibet is made up mainly of valleys and is situated between the Kangdese Mountains and the Himalayas. The eastern section is comprised largely of canyons and is marked by a gentle drop in altitude interspersed with small mountain ranges known as the Henduan.