Photo taken on April 18, 2014 shows the snow-covered Bayan Har Mountains in Chindu County of Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. Yushu Prefecture was hit by a snow on Friday. The prefecture is home to the uppermost drainage areas of three major Asian rivers: the Yellow River, the Yangtze and the Mekong. (Xinhua/Zhang Hongxiang) 

Two yaks walk on a snow carpet at the foot of the Bayan Har Mountains in Chindu County of Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province, April 18, 2014. Yushu Prefecture was hit by a snow on Friday. The prefecture is home to the uppermost drainage areas of three major Asian rivers: the Yellow River, the Yangtze and the Mekong. (Xinhua/Zhang Hongxiang) 

A yak rests on a snow carpet at the foot of the Bayan Har Mountains in Chindu County of Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province, April 18, 2014. Yushu Prefecture was hit by a snow on Friday. The prefecture is home to the uppermost drainage areas of three major Asian rivers: the Yellow River, the Yangtze and the Mekong. (Xinhua/Zhang Hongxiang) 

Photo taken on April 18, 2014 shows the snow-covered Bayan Har Mountains in Chindu County of Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. Yushu Prefecture was hit by a snow on Friday. The prefecture is home to the uppermost drainage areas of three major Asian rivers: the Yellow River, the Yangtze and the Mekong. (Xinhua/Zhang Hongxiang)