First Austrian Republic

The Republic of Austria is the period of Austrian history after the signing of the Treaty of Saint-Germain-en-Laye of September 1919. It went through the settlement after the end of World War I which put an end to the Republic of German-Austria. It continued up to World War II. Austria was a "de-facto" republic, but its official name was the Federal State of Austria. 
This period was had a lot of conflict between the left and the right. The July Revolt of 1927 was an example. The Constitution of Austria was started in 1920 and changed in 1929. The Federal State (sometimes called the First Republic) came to an end with the "Anschluss" to Nazi Germany in 1938. Some people say the end came with the start of the Austro-fascist dictatorship in 1933/34 following the Austrian Civil War.