German Drau
River, south-central Europe.
It rises in the Carnic Alps and flows east through Austria, where it forms the Drautal, the longest longitudinal valley of the Alps . Flowing southeast, it passes through Slovenia and forms part of the Croatian-Hungarian border. The Drava is 447 mi (719 km) long and a major tributary of the Danube River . Its valley was the chief passage through which invaders penetrated the Alpine countries.