Austria
The Treaty of Saint-Germain of 1919 (for Hungary the Treaty of Trianon of 1920) confirmed and consolidated the new order of Central Europe which to a great extent had been established in November 1918, creating new states and altering others. The German-speaking parts of Austria which had been part of Austria-Hungary were reduced to a rump state named The Republic of German-Austria (German: "Republik Deutschösterreich"). The desire for "Anschluss" (annexation of Austria to Germany) was a popular opinion shared by all social circles in both Austria and Germany. On 12 November, German-Austria was declared a republic, and named Social Democrat Karl Renner as provisional chancellor. On the same day it drafted a provisional constitution that stated that "German-Austria is a democratic republic" (Article 1) and "German-Austria is an integral part of the German reich" (Article 2). The Treaty of Saint Germain and the Treaty of Versailles explicitly forbid union between Austria and Germany. The treaties also forced German-Austria to rename itself as "Republic of Austria" which consequently led to the first Austrian Republic.
Anschluss
The idea of an "Anschluss" (a united Austria and Germany that would form a "Greater Germany") began after the unification of Germany excluded Austria and the German Austrians from the Prussian-dominated German Empire in 1871. Following the end of World War I with the fall of the Austro-Hungarian Empire, in 1918, the newly formed Republic of German-Austria attempted to form a union with Germany, but the Treaty of Saint Germain (10 September 1919) and the Treaty of Versailles (28 June 1919) forbade both the union and the continued use of the name "German-Austria" ("Deutschösterreich"); and stripped Austria of some of its territories, such as the Sudetenland.