Team members lead the yaks slowly down the mountain during a border patrol in northwest China's Xinjiang Uygur Autonomous Region, Dec. 25, 2020. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)

Team members ride on yaks during on a border patrol in northwest China's Xinjiang Uygur Autonomous Region, Dec. 25, 2020. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)

Team members feed a yak before going on a border patrol in northwest China's Xinjiang Uygur Autonomous Region, Dec. 25, 2020. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)

Team members ride on yaks during a border patrol in northwest China's Xinjiang Uygur Autonomous Region, Dec. 25, 2020. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)

A team member checks a yak's hoof injury during a border patrol in northwest China's Xinjiang Uygur Autonomous Region, Dec. 25, 2020. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)

Team members go on a border patrol with yaks in northwest China's Xinjiang Uygur Autonomous Region, Dec. 25, 2020. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)

A team member drags a fractious yak on a frozen river during a border patrol in northwest China's Xinjiang Uygur Autonomous Region, Dec. 25, 2020. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)

Team members go on a border patrol with yaks in northwest China's Xinjiang Uygur Autonomous Region, Dec. 25, 2020. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)

Aerial photo taken on Dec. 25, 2020 shows team members walking on a frozen river with yaks during a border patrol in northwest China's Xinjiang Uygur Autonomous Region. A division of Xinjiang Production and Construction Corps in Yecheng County of Tumxuk is stationed in the hinterland of the Kunlun Mountains at an average altitude of about 4,000 meters. A team in the Corps regularly heads towards the mountain peaks and patrols the border with yaks. (Xinhua/Hu Huhu)