Photo taken on Sept. 5, 2014 shows a primitive forest in the Zhagana region in Diebu County of Gannan Tibetan Autonomous Prefecture in northwest China's Gansu Province. Zhagana is a mountainous region on the northeastern rim of the Tibetan Plateau, with an average altitude of 3,500 meters. The region has a unique cultural and natural landscape featuring Tibetan-style villages, primitive forests and mountains formed during the quatenary glaciation. (Xinhua/Zhang Meng)