Is there a specific expression to denote territories which were once occupied?

I have to write a long History essay about territories which were once occupied by one people, but no longer are. Is there a term for that, something like once-[insertpeoplehere]-occupied?

Solution 1:

If the fact that the country was at the time occupied is important, such as wartime, use then-occupied

He was sent to then-occupied France to serve in a battalion of former Soviet prisoners of war...

https://www.history101.com/sides-wwii-yang-kyoungjong/

By April of 1945, eight months following Nazi massacres in the Saulx valley of then-occupied France,

https://www.amazon.com/Elbe-Resolution-Lloyd-Holm/dp/0984765433

If the country was occupied as a colony or dominion, then use French Senegal, British India, etc., again if the fact of occupation is relevant to the issue.