Tibetannet

In this combo photo, the left part taken by Ren Yongzhao and released on Dec. 24, 1964 shows a view of Qamdo City of southwest China's Tibet Autonomous Region; the right part is an aerial photo taken by Sun Fei on March 25, 2021 showing a view of Karub District of Qamdo City. (Xinhua)

LHASA, Aug. 18 (Xinhua) -- 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.

Aerial photo taken on May 10, 2020 shows glacier near the advance camp at an altitude of 6,500 meters on Mount Qomolangma. (Xinhua/Sun Fei)

Aerial photo taken on Oct. 7, 2020 shows a night view of Qamdo City of southwest China's Tibet Autonomous Region. (Xinhua/Jigme Dorje)

Aerial photo taken on Aug. 24, 2020 shows the Sijijixiang Village, a relocation village, of Caina Township in Quxu County, southwest China's Tibet Autonomous Region. It was among the first relocation sites for poverty alleviation in the region. (Xinhua/Sun Fei)

Aerial photo taken on Sept. 21, 2020 shows a poverty-relief relocation village of Zongang County in Qamdo City, southwest China's Tibet Autonomous Region. (Xinhua/Jigme Dorje)

Aerial photo taken on Oct. 27, 2019 shows a long-span bridge on the Sichuan-Tibet Highway in Tangmai, southwest China's Tibet Autonomous Region. (Xinhua/Sun Fei)

Aerial photo taken on June 5, 2019 shows a view of Lhalu Wetland National Nature Reserve in Lhasa, southwest China's Tibet Autonomous Region. (Xinhua/Purbu Zhaxi)

Combo photo shows a view of Lhasa City of southwest China's Tibet Autonomous Region in 1955 (up, taken by Lan Zhigui) and on Aug. 10, 2019 (bottom, taken by Li Xin) respectively. (Xinhua)

In this combo photo, the upper part taken by Gu Shoukang and released on Nov. 30, 1979 shows a view of Zedang Township in southwest China's Tibet Autonomous Region; the lower part is an aerial photo taken by Cering Lungbu on Nov. 26, 2020 showing a view of the same township. (Xinhua)

In this combo photo, the upper part taken by Xu Bang and released on March 17, 1971 shows a view of Shiquanhe Township in Ngari of southwest China's Tibet Autonomous Region; the lower part is an aerial photo taken by Sun Ruibo on May 21, 2021 showing a view of the same township. (Xinhua)

In this combo photo, the upper part taken by Cai Long and released on Jan. 9, 1981 shows a view of Medog County before its access to any highway in southwest China's Tibet Autonomous Region; the lower part is an aerial photo taken by Sun Fei on Feb. 13, 2021 showing a view of the same county, which has ended its isolation from the outside in 2013 with the opening of a highway. (Xinhua)

Combo photo shows a view of Bayi Township in Nyingchi, southwest China's Tibet Autonomous Region in 1991 (up, taken by Chen Xie) and on July 20, 2021 (bottom, taken by Purbu Zhaxi) respectively. (Xinhua/Purbu Zhaxi)