In this combo photo, the upper part taken by Ren Yongzhao shows engineering investigation workers drilling at the selected site of Lhasa hydroelectric power station in 1950s, and the lower part taken by Dong Zhixiong shows a view of the Zam Hydropower Station in southwest China's Tibet Autonomous Region, Oct. 26, 2018. 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)
