First Austrian Republic
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.