A film salutes grassroots officials enduring extreme altitudes, separation, and sacrifice while transforming lives in Xizang's remote regions, Xu Fan reports.

When filmmaker Cai Yu ventured deep into Tsonyi county in the Xizang autonomous region — the country's highest county with an average altitude exceeding 5,000 meters — to shoot a documentary in 2015, one interview stayed with him long after filming ended.

The subject was Deng Jiping, a local government official originally from Sichuan province, who has worked in Xizang for more than two decades, much of that time living apart from his family. Deng recalled a painful moment when his wife once told him he was an unqualified father. Their son, she said, jokingly called him "phone dad", because Deng could return home to see his family only a few times each year.

Through more interviews with officials who have overcome challenges ranging from altitude sickness, to isolation and years of separation from loved ones, Cai was moved by their dedication. Over the next four years, he developed a script inspired by their experiences. The result was Puruo Gangri, a feature-length movie that was released on the Chinese mainland in December.