Munich Agreement
Czechoslovakia was an independent country since it had been formed in 1918. After the First World War this was done by  international agreement. Adolf Hitler wanted Lebensraum (meaning "living space") to have all Germans in Czechoslovakia united with Germany. As most German speakers in Czechoslovakia were in the Sudetenland, Hitler set his sights there first. He knew that was the main industrial strength of Czechoslovakia. Britain, France and the Soviet Union had all agreed to support Czechoslovakia if it was invaded.