In this combo photo, the left part taken by Basang shows a herdsman learning to ride a bicycle in Nyainrong County in 1980s; and the right part taken by Chogo on Feb. 23, 2017 shows a youngster posing with a motorcycle in Nyainrong County, Nagqu, southwest China's Tibet Autonomous Region. 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)