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.

Photo taken on Sept. 11, 2018 shows the ruins of the Guge Kingdom in Zanda County of Ngari Prefecture, southwest China's Tibet Autonomous Region.

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.

Photo taken on Oct. 22, 2014 shows the ruins of the Guge Kingdom in Zanda County of Ngari Prefecture, southwest China's Tibet Autonomous Region.

Photo taken on Sept. 11, 2018 shows 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.

Photo taken on Sept. 10, 2018 shows roads to the ruins of the Guge Kingdom in Zanda County of Ngari Prefecture, southwest China's Tibet Autonomous Region.

Photo taken on Sept. 14, 2018 shows the unique landscape of "earth forest" in Zanda County of Ngari Prefecture, southwest China's Tibet Autonomous Region.

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. (Photos: Xinhua/Purbu Zhaxi)

Photo taken on Sept. 10, 2018 shows the unique landscape of "earth forest" in Zanda County of Ngari Prefecture, southwest China's Tibet Autonomous Region.