Around 400 B.C., Celtic peoples from Western Europe settled in the eastern Alps. A Celtic state, Noricum, developed around the region's ironworks in the second century B.C. The Romans occupied Noricum without resistance in 9 B.C. and made the Danube River the effective northern frontier of their empire.
North of the Danube, various German tribes were already extending their territory. By the latter half of the second century A.D., they were making devastating incursions into Roman territories. Nevertheless, Roman arms and diplomacy maintained relative stability until the late fourth century, when other Germanic tribes, including the Ostrogoths, Visigoths, and Vandals, were able to establish settlements in Roman territory south of the Danube. The Roman province gradually became indefensible, and much of the Christian, Romanized population evacuated the region in 488. In 493 the Ostrogoths invaded Italy, seized control of what remained of the western half of the Roman Empire, and brought the Roman era in the eastern Alps to an end.
Data as of December 1993