Photo taken on Sept. 10, 2018 shows a valley to the ruins of the Guge Kingdom in Zanda County of Ngari Prefecture, southwest China's Tibet Autonomous Region. Zanda features the unique landscape of "earth forest" and well-preserved Guge Kingdom site. The ancient Guge Kingdom was founded around the 9th century but disappeared mysteriously during the 17th century. Ngari, at an average altitude of 4,500 meters, is nicknamed the "top of the roof of the world." It has always been the crown jewel for adventurers and archaeologists, and after them came tourists. (Xinhua/Purbu Zhaxi)