In this combo photo, the upper part taken by Wang Chunde in the 1950s and the lower part taken by Chogo on Aug 13, 2021 shows views of Barkhor Street in Lhasa, 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. [Photo/Xinhua]

In this combo photo, the left part taken by Tudain shows Lhazhoen, a businesswoman, talking to a client though a mobile phone in 1994; and the right part taken by Jigme Dorje on June 25, 2021 shows a passenger taking a selfie with a Fuxing bullet train on the Lhasa-Nyingchi railway, Southwest China's Tibet autonomous region. [Photo/Xinhua]

In this combo photo, the upper part taken by Wang Chunde in the 1950s and the lower part taken by Sun Fei on Aug 9, 2021 shows views of the Lhasa Bridge, Southwest China's Tibet autonomous region. [Photo/Xinhua]

In this combo photo, the upper part taken by Ren Yongzhao shows vehicles running on a suburban road toward the Potala Palace in the 1950s, and the lower part taken by Zhang Rufeng shows vehicles running on a street toward the Potala Palace on Aug 9, 2021 in Lhasa, Southwest China's Tibet autonomous region. [Photo/Xinhua]

In this combo photo, the upper part provided by the Tibet Daily in the 1980s and the lower part taken by Jigme Dorje on Aug 9, 2021 shows views of a market in Lhasa, Southwest China's Tibet autonomous region. [Photo/Xinhua]

In this combo photo, the upper part provided by the Tibet Daily in the 1980s and the lower part taken by Jigme Dorje on Aug 9, 2021 shows views of a market in Lhasa, Southwest In this combo photo, the upper part taken by Cheng Xi shows children riding on a merry-go-round at a kindergarten in Xigaze in the 1980s; and the lower part taken by Zhang Rufeng on Aug 9, 2021 shows a view of an amusement park in Lhasa, Southwest China's Tibet autonomous region. [Photo/Xinhua]China's Tibet autonomous region. [Photo/Xinhua]

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, Nagchu, Southwest China's Tibet autonomous region. [Photo/Xinhua]

In this combo photo, the upper part taken by Lan Zhigui in the 1960s and the lower part taken by Purbu Zhaxi on Aug 9, 2021 shows views of the west suburbs of Lhasa, Southwest China's Tibet autonomous region. [Photo/Xinhua]

In this combo photo, the upper part taken by Ren Yongzhao shows residents buying tea kettles in Lhasa in the 1950s; and the lower part taken by Purbu Zhaxi on Dec 12, 2011 shows a villager using a blender to make butter tea for her family in Shigatse, Southwest China's Tibet autonomous region. [Photo/Xinhua]

In this combo photo, the upper part taken by Ren Yongzhao shows patients walking to the doctors' offices at Lhasa People's Hospital in the 1950s; and the lower part taken by Sun Ruibo on April 19, 2021 shows surgeons of Lhasa People's Hospital using a robot to perform an orthopaedic surgery under the remote guidance of experts from Beijing Jishuitan Hospital through 5G communication technology in Lhasa, Southwest China's Tibet autonomous region. [Photo/Xinhua]

Combo photo shows hunter Daqian of Qionglin village in 1950s (L, file photo) and Daji, a former hunter, working as a farmer and forest ranger now in Qionglin village of Mainling county in Nyingchi, Southwest China's Tibet autonomous region, June 19, 2021 (R, photo taken by Jigme Dorje). [Photo/Xinhua]

In this combo photo, the upper part taken by Ren Yongzhao shows primary school students practicing drawing in front of the Potala Palace in the 1950s; and the lower part taken by Chogo on Nov 10, 2017 shows doctorate holders who were indigenously cultivated in Southwest China's Tibet autonomous region. [Photo/Xinhua]

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. [Photo/Xinhua]

Combo photo shows a rattan bridge over the Yarlung Zangbo River in 1980s (L, photo taken by Gu Shoukang) and Mainling section of the highway linking Pad township in the city of Nyingchi and Metog county, Southwest China's Tibet autonomous region, on Nov 5, 2020 (R, photo taken by Dong Zhixiong). [Photo/Xinhua]

Combo photo shows a view of Beijing Middle Road in Lhasa, Southwest China's Tibet autonomous region in the 1980s (up, taken by Che Gang) and on Aug 9, 2021(bottom, taken by Jigme Dorje) respectively. [Photo/Xinhua]

Combo photo shows mountaineering team members walking on a snow slope at an altitude of over 7,000 meters in 1960 (up, file photo) and the equipment of Chinese surveyors on Mount Qomolangma, May 21, 2020 (bottom, photo taken by Lhagba). [Photo/Xinhua]

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. [Photo/Xinhua]

In this combo photo, the upper part taken by Wang Chunde in 1959 and the lower part taken by Purbu Zhaxi on Aug 13, 2021 shows a view of Barkhor Street in Lhasa, Southwest China's Tibet autonomous region. [Photo/Xinhua]

Combo photo shows boats made from cowhide carrying grain and products on the Yarlung Zangbo River in 1950s (up, photo taken by Zhao Qi) and a grand bridge over the Yarlung Zangbo River in Zhanang county of Shannan city, Southwest China's Tibet autonomous region, Dec 11, 2016 (bottom, photo taken by Purbu Zhaxi). [Photo/Xinhua]

Combo photo shows a view of Bayi town in Nyingchi, Southwest China's Tibet autonomous region in the 1990s (up, taken by Chen Xie) and on July 20, 2021(bottom, taken by Purbu Zhaxi) respectively. [Photo/Xinhua]

Combo photo shows a view of Shigatse city, Southwest China's Tibet autonomous region in the 1960s (up, file photo) and on Aug 9, 2021(bottom, taken by Chogo) respectively. [Photo/Xinhua]

In this combo photo, the upper file photo shows women and children begging for food on the street under the serf system in old Tibet; and the lower part taken by Sun Ruibo on March 13, 2021 shows Losan Zhoima, founder of a model and aesthetic education training institution for children, teaching kids in Lhasa, Southwest China's Tibet autonomous region. [Photo/Xinhua]

Combo photo shows a view of Lhasa Middle School in Lhasa, Southwest China's Tibet autonomous region in the 1950s (up, taken by Jing Jiadong) and on Aug 9, 2021 (bottom, taken by Sun Ruibo) respectively. [Photo/Xinhua]

In this combo photo, people buy goods at a shop in 1980s (up, photo taken by Liu Lijia), and people visit the Wanda Shopping Mall in Lhasa, Southwest China's Tibet autonomous region, Aug 15, 2021 (bottom, photo taken by Sun Fei). [Photo/Xinhua]