Shenxianwan border post is located in the middle of Karakoram Mountains, northwest China’s Xinjiang Uygur Autonomous Region. The post is 5,380 meters above the sea level, with average temperature below zero. The maximum temperature difference between the day and the night here is over 30 Celsius degrees, and it has more than 180 strong windy days a year. The oxygen content in the air is less than 45 percent of that of the inland and the ultraviolet intensity is 50 percent higher.