The Flaming Mountains () or Huoyan Mountains, are barren, eroded, red sandstone hills in the Tian Shan of Xinjiang. They lie near the northern rim of the Taklamakan Desert and east of the city of Turpan. Their striking gullies and trenches caused by erosion of the red sandstone bedrock give the mountains a flaming appearance at certain times of the day. The mountains are approximately long and wide, crossing the Turpan Depression from east to west. The average height of the Flaming Mountains is , with some peaks reaching over . The mountain climate is harsh and the extremely high summer temperatures make this the hottest spot in China, frequently reaching or higher. One of the largest thermometers in China is on display adjacent to the mountain, tracking the surrounding ground temperatures. It is a popular tourist spot. A number of important palaeontological remains have been found in the area, see e.g. Lianmuqin Formation and Subashi Formation. In ancient times, the merchant traders traversing the Silk Route in Southeast Asia avoided the mountains by stopping at oasis towns, such as Gaochang, built on the desert's rim at the foot of the Flaming Mountains and near an important mountain pass. Oasis towns became respite stops for traveling merchant traders. Buddhist missionaries often accompanied traders on busy international trade routes. During this time trade boomed on the Silk Route. Buddhist monasteries and temples were built in the busy trading centers and in nearby remote mountain spots. The Bezeklik Thousand Buddha Caves site lies in a gorge under the cliffs of the Flaming Mountains near the pass by Gaochang. It is a complex of seventy Buddhist cave grottoes dating from the 5th to the 9th centuries CE, many with thousands of murals of Buddha. The Flaming Mountains received their name from a fantasy account of a Buddhist monk, accompanied by a Monkey King with magical powers. The monk runs into a wall of flames on his pilgrimage to India in the popular 16th century novel Journey to the West by Ming dynasty writer, Wu Cheng'en.