Ruthenia's population of around 500,000 is around 60% Ruthenian (related to Ukrainian) with with Slovak, Polish and Hungarian minorities. Most Ruthenians are neither Orthodox nor Catholic, but Uniate (Greek Catholic.)
Following Hitler's annexation of the Sudetenland, Poland, Hungary and Russia invaded parts of Czechoslovakia and Slovakia prepared to break away, Ruthenia considering seceding. It eventually did so in March 1939, and was invaded and annexed by Hungary the next day. This makes it quite probably the world's shortest lived state. | 
