Vilnius Region[a] is the territory in present-day Lithuania and Belarus that was originally inhabited by ethnic Baltic tribes and was a part of Lithuania proper, but came under East Slavic and Polish cultural influences over time.

The Republic of Central Lithuania, commonly known as the Central Lithuania, and the Middle Lithuania, was an unrecognized short-lived puppet state of Poland, that existed from 1920 to 1922. It was founded on 12 October 1920, after successful Żeligowski's Mutiny, during which the volunteer 1st Lithuanian–Belarusian Division under command of general Lucjan Żeligowski seized the Vilnius Region that Lithuania made claims to. It was incorporated into Poland on 18 April 1922.