The early ancestors of the Austrian Empire’s people were the Slavs and the Bavarii, who moved into Austria after the Roman Empire fell. Eventually, Bavaria took over the Slavic part of the country. Bavaria was a territory in Austria and the Austrian Empire for many centuries. Today, it is a part of Germany.
The ethnicity of Austria is technically Austrian, but this is very similar to German. There are also many minority groups in Austria, the largest of which are the Turks. German is the official language of Austria.
Ms. Ouellet's Social Studies Blog 