In this combo photo, the left part taken by Chen Zonglie shows Chinese mountaineers boiling ice at a camping site at an altitude of 5,700 meters in 1960s, and the right part taken by Sun Fei shows a staff member cooking in the advance camp at an altitude of 6,500 meters in southwest China's Tibet Autonomous Region, May 10, 2020. On May 23, 1951, the Agreement of the Central People's Government and the Local Government of Tibet on Measures for the Peaceful Liberation of Tibet (17-Article Agreement) was signed, officially proclaiming the peaceful liberation of Tibet. The year 2021 marks the 70th anniversary of the historic event. (Xinhua)
