A yak is seen in Hoh Xil in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province, Dec. 1, 2016. Hol Xil has an average altitude of over 4,600 meters, making it an ideal habitat for Tibetan antelopes, kiangs and other animals. It was enlisted as one of the UNESCO's World Natural Heritages in July 2017. (Xinhua/Wu Gang)