Early Third Reich Advances

Germany's first direct military advances in violation of the Treaty of Versailles were all in the direction of German people, who were always German speaking people. The occupation of the Rhineland , the Anschluss , the invasion of the Sudetenland and Poland. There were certainly a variety of reasons for the Third Reich to go to war, and as racialist as the Reich and Hitler were, it can't be seen as surprising that they would reach for Germans first. Perhaps someone even calculated that by doing so, they would be staying below the radar of potential opponents.

No one can argue that the geography prevented other attacks from being contemplated. It can't be argued that the Sudetenland or Poland were major military concerns of the Third Reich, and hence needed to be taken out first. And no one can argue that either Czechoslovakia or Poland were the richest spoils to be taken on the German borders, since that honor would have to go to Holland and Belgium.

Rhineland	German land and German speakers
Autria	Often united with Germany before 1866 Austria: Largest German speaking country outside Germany (Austro-Prussian War of 1866?)
Sudetenland	German speaking minority in Czechoslovakia(Bohemia) (now Czech Republic) Taken away from Germany after the first World War.
Poland	Millions of german speakers, also cut after the first World War

Official German propaganda regularly mentioned the treatment of Germans in other countries as a disgrace that need to be righted. However, these people were often just called Germans, and it was probably more race, than language, that encouraged the German to agree with the propaganda.