Carpathian Ruthenia
In 1919, after the American-Rusyns agreed with Tomáš Masaryk to incorporate Carpathian Ruthenia into Czechoslovakia, the whole of Carpathian Ruthenia was occupied by Czechoslovak troops. On June 4, 1920, Mukachevo officially became part of Czechoslovakia by the Treaty of Trianon. In November 1938, a part of the territory of the former Kingdom of Hungary was re-annexed by Hungary as part of the First Vienna Award.