[1] Once Adolf Hitler completed the union between Austria and Germany (Anschluss), the Nazi government renamed the incorporated territory.

The name Austria (Österreich in German, meaning "Eastern Realm") was at first replaced by "Ostmark", referring to the 10th century Marcha orientalis.

According to the Ostmarkgesetz with effect from 1 May 1939, the former States of Austria were reorganized into seven Reichsgaue of the German Reich, each under the rule of a government official holding the dual offices of Reichsstatthalter (governor) and Gauleiter (Nazi Party leader):[2] A Reichsgau was a new, simple administrative sub-division institution which replaced the federal states in the otherwise completely centralized Third Reich.

[3] From April 8, 1942, as the term "Ostmark" was still too reminiscent of the old, independent state of Austria, the chosen official name for the seven entities was Alpen- und Donau-Reichsgaue ("Danubian and Alpine Reichsgaue").

In the course of the Allied occupation after World War II, the Austrian state was restored in its pre-1938 borders according to the 1943 Moscow Declaration.