Province, Roman Empire, corresponding to modern western Hungary and parts of eastern Austria and Slovenia, as well as portions of several Baltic states, primarily Slovenia, Croatia, and Serbia (Vojvodina). The original inhabitants were mainly Illyrians, with some Celts in the western part. Conquered by Rome beginning in 35 BC, the people of Pannonia revolted in AD 6, posing the greatest threat to the empire since Hannibal's invasion. Pannonia was split in AD 106, and Pannonia Superior became a centre of the Roman wars under Marcus Aurelius. The Romans withdrew from the area after 395.