The Sudetenland was taken away from Germany and the Austro-Hungarian Empire and given to Czechoslovakia.
The Sudetenland contained 3.5 million Germans who had been cut off from the rest of Germany after the creation of Czechoslovakia by the Treaty of Versaille. Hitler felt he had a rightful claim over the Sudetenland because he saw it as German land. Also, Sudeten Germans claimed they were mistreated by the Czech government and wanted home rule or union with Germany. Britain was reluctant to get involved because she had inadequate armed forces to do so and had no treaty agreement to Czechoslovakia.
Hitler then said he would only the part of the Sudetenland that belonged to Germany (had German nationals in it). The League of Nations obliged and Hitler was allowed to take the part of the Sudetenland that he wanted. After witnessing the ease of taking half of the Sudetenland Hitler then proceeded to ask for the whole Sudetenland. He wasnt happy with merely one piece of Czechoslovakia, Hitler planned to take the whole. 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.
The bigger nations were did not react to Hitler’s demands because they were following appeasement and wanted to keep Hitler at bay. Also they felt threatened by Germany and Hitler’s progress into re arming as he was able to get the nation out of the depression faster than any of the other European nations. Secondly, although Britain, France and the USSR did not act upon there pacts to protect Czechoslovakia. The League of Nations were proved useless against Germany as they did not act accordingly as to Hitler’s actions, they simply sit back and watched him do as he pleased.