Villagers walk on the frozen Puma Yumco Lake to send supplies to herders on the islands in Dowa village in Nakartse county, Southwest China's Tibet autonomous region, Feb 9, 2017. It is the coldest point of the year in Tibet, and time for the annual migration of herds of sheep across an icy lake, a dangerous and exhilarating ancient practice. At Dowa village, 5,070 meters above sea level, thousands of sheep were taken across frozen water to two islands on Puma Yumco Lake, one of the world's highest lakes. The migration started before dawn. Hundreds of sheep move forward, one after another, and the icy surface squeaks under the enormous weight of the animals. When smaller animals wander off and fall, the herders take them back by carrying them in their arms. It takes more than two hours to complete the three-kilometer journey across the frozen lake. Herders will spend a month with the animals on the islands, where grass grows to waist height. [Photo/Xinhua]