Films can be about history, films have a history, films affect history, and history affects films. This page give pointers to finding resources on each of these.
To find resources on the history of the US and other countries, see the list of History Subject Guides.
Here are some examples of subject headings that you can use to search Orbis:
See the appropriate history subject guides for help in finding subject headings about a country's history.
For articles about history in movies or the history of film, refer to the Articles page.
But you should also check the history databases, since historians study the role of films in history as well as how history is represented in films -- and their articles may appear in journals that the film databases don't cover.