 On the right shore of the Danube, the lower Leitha River marked the Imperial–Hungarian border for centuries.In the south, Austria bordered the Styrian lands which were likewise elevated to a duchy, and unified with Austria in 1192.The territory originally inhabited by Celts was for centuries crossed in transit by several Germanic tribes and from the 6th century onwards settled by Avars as well as by Slavic tribes, who about 600 founded the independent principality of Carantania in the south.