Mountains and Rivers Bearing Witness comprehensively presents the Chinese people's arduous 14-year struggle against aggression, tracing events from the September 18 Incident in 1931 — which marked the outbreak of the war — to Japan's unconditional surrender on Aug 15, 1945.

The documentary was in production for over three years, with the crew visited 37 archives across the country to collect a wealth of rare photographs and video footage. Notably, 40 percent of the material is being screened for the first time.

Among the most valuable finds are film reels shot by former Soviet director Roman Karmen, who was dispatched to China in 1938 to document the Chinese resistance. Another rarely told aspect of history, featured in the film, is the presence of (former) Soviet Air Force volunteers who assisted Chinese pilots during the 1938 Battle of Wuhan, according to director Huang Yue.