When the Romans conquered the region that is now Austria about 14 B.C., it was inhabited by Celts. Germanic tribes beyond the Danube River attacked the area frequently during the Roman era. In the fourth century the Germans, driven westward by the Huns, began settling on the south side of the river and taking over the Roman provinces.

The Franks gained dominance over the rest of the Germans and over the Slavs who had crossed the Danube late in the sixth century. To hold off attacks of the barbarian Avars, Charlemagne, king of the Franks (771–814), set up a military district, the Ostmark, in the southern half of the present province of Lower Austria.

In the late ninth century, when Frankish power had weakened, the district was over-run by northern Slavs and Magyars (Hungarians). In 955 the German king (later Holy Roman Emperor) Otto the Great defeated the Magyars and restored the Ostmark. Many German colonists were settled in it, and in 976 it was placed under the House of Babenberg. The boundaries were extended east and north by conquest, and Vienna became the capital.

Important dates in Austria
15 B.C. The Romans controlled Austria south of the Danube River.
A.D. 100's Warlike tribes from the north began to invade Roman Austria, and Roman control started to weaken.
476 The Roman Empire collapsed.
976 The Holy Roman emperor gave control of northeastern Austria to Leopold I of the Babenberg family.
1278 Rudolf I, a Habsburg, began to acquire the Babenberg territory and nearby lands for his family.
1438-1806 The Archduchy of Austria was the most important state in the Holy Roman Empire.
1867 Austria-Hungary was established.
1914-1918 Austria-Hungary was defeated in World War I.
1918 The Habsburgs were overthrown, and Austria became a republic.
1938 Adolf Hitler made Austria part of Germany.
1939-1945 The Allies defeated Germany in World War II.
1945-1955 Britain, France, the Soviet Union, and the United States occupied Austria.
1995 Austria joined the European Union, an economic and political organization of European nations.