/r/AskHistorians may not be the ideal place to ask this, so you may want to try /r/History or /r/Movies as well, as this isn't strictly history.

With that in mind, I can think of two movies which fit the bill.

Empire of the Sun is the story of a wealthy English boy who lives in the Shanghai international quarter who is sent to a Japanese internment camp.

The Painted Veil tells the story of a doctor and his estranged wife during a cholera epidemic in rural China during the civil war period. Although it's based on fictional romance novel of the 1920s, it sets the scene pretty well. It includes the Nationalists, local warlords, foreigners lives in china, among other things.

This is a fascinating and turbulent time in Chinese history, so feel free to start a new thread asking any questions about it.