

In 1938, Hitler turned his attention to the Sudeten area of Czechoslovakia.
The nation of Czechoslovakia had been created after WWI. Two Slavic peoples, the Czechs and the Slovaks, came together to form the country along with three million German speakers from the Sudeten area on the border with Germany, and smaller numbers of Hungarians, Ukrainians and Poles. The 20 years since its creation had seen its democracy and economy flourish.
The main threat to the fledgling nation was from Hitler's plans for expansion and from the Sudeten Germans who, used to being part of the German-speaking Austrian empire, were not happy at their inclusion in a Slav-controlled state.
By March 1938, Hitler had successfully invaded Austria without a shot being fired. With one major German-speaking territory under his control he then turned his attention to another - the Sudeten area of Czechoslovakia.
Hitler wanted to use the Sudeten Germans to create trouble in Czechoslovakia and, as he had in the Rhineland and Austria, use this as a pretence for invading and "restoring order".
Not content with merely one piece of Czechoslovakia, Hitler planned to smash the country. The Czechs and Slovaks were of Slavic origin and, according to Hitler's racial proclamations that the German/Aryan people were superior to other races, they were considered Untermenschen (subhuman).

Czechoslovakia 1933
Hitler financed and supported the Sudeten German Party under Conrad Henlein. With Hitler's backing the party became a force to be reckoned with in Czechoslovakia.