LEFT: This file photo taken at a certain time before 1949 shows a Derung resident climbing a cliff-side ladder in Dulongjiang Township of Gongshan Derung and Nu Autonomous County, southwest China''s Yunnan Province. RIGHT: Derung villager Li Yongming accompanies his grandmother Dang Na as they climb up cement steps to reap fodder grass from the mountains in Dulongjiang Township of Gongshan Derung and Nu Autonomous County, southwest China''s Yunnan Province, Oct. 31, 2020. (Photo taken by Hu Chao) (Xinhua)