The Qinghai-Tibet Plateau is China's largest plateau, and also the world's highest plateau. Therefore, it is known as the "Roof of the World." The Qinghai-Tibet Plateau covers an area of 2.4 million square kilometers, with most elevations being above 3500 meters. It includes all of Tibet and Qinghai, western Sichuan, southern Xinjiang, and parts of Gansu and Yunnan provinces. Around the plateau are many high mountains: to the south lies the Himalayas, to the north lie the Altun Mountains, Kunlun Mountains, and Qilian Mountains, to the west lies the Karakoram Mountains, and to the east lie the Hengduan Mountains. Within the plateau, there are also the Tanggula Mountains, Gangdisi Mountains, Nyainqentanglha Mountains, and more. Most of these mountains exceed 5500 meters in height, and among them, the Himalayas have 16 peaks that exceed 8000 meters. The plateau is divided by mountains into many basins and wide valleys. There are numerous lakes, such as Qinghai Lake and Namtso, which are all inland saltwater lakes rich in salt, borax, mirabilite, and other resources. The plateau is the birthplace of many major rivers in Asia, including the Yangtze River, Yellow River, Lancang River, Nu River, and Yarlung Zangbo River, all of which originate here, providing abundant hydropower resources. Due to its high elevation, most areas lack sufficient heat; in places above 4500 meters, the average temperature of the hottest month is less than 10 degrees Celsius, and there is no frost-free period, making it difficult for grains to mature. These areas are only suitable for grazing, with livestock mainly consisting of cold-resistant yaks, Tibetan sheep, and Tibetan goats. In river valleys below 4200 meters, crops can be planted, mainly cold-resistant varieties such as barley, wheat, peas, potatoes, and rapeseed. The Yarlung Zangbo River Valley has a lower latitude, so winters are not severely cold, allowing wheat to safely survive the winter. There are already many hydropower stations, coal mines, steel plants, chemical plants, wool textile factories, paper mills built on the plateau. Currently, there are four highways leading into the plateau: the Sichuan-Tibet, Qinghai-Tibet, Yunnan-Tibet, and Xinjiang-Tibet highways. A railway will also soon be constructed on the plateau. Civil aviation flights are available to Xining, Golmud, and Lhasa.