Its original inhabitants were the Pannonii (sometimes called Paeonii by the Greekss). From the 4th century BC it was invaded by various Celtic tribes. Little is heard of Pannonia until 35 BC, when its inhabitants, allies of the Dalmatians, were attacked by Augustus, who conquered and occupied Siscia (Sisak). The country was not, however, definitely subdued until 9 BC, when it was incorporated with Illyria, the frontier of which was thus extended as far as the Danube. In A.D. 7 the Pannonians, with the Dalmatians and other Illyrian tribes, revolted, and were overcome by Tiberius and Germanicus, after a hard-fought campaign which lasted for two years. The proximity of dangerous barbarian tribes (Quadi, Marcomanni) necessitated the presence of a large number of troops (seven legions in later times), and numerous fortresses were built on the bank of the Danube.
Some time between the years 102 and 107, between the first and second Dacian wars, Trajan divided the province into Pannonia superior (the western), and inferior (the eastern) portion. According to Ptolemy, these divisions were separated by a line drawn from Arrabona (Raab) in the north to Servitium (Gradiška) in the south; later, the boundary was placed farther east. The whole country was sometimes called the Pannonias (Pannoniae). Pannonia superior was under the consular legate, who had formerly administered the single province, and had three legions under his control: Pannonia inferior at first under a praetorian legate with a single legion as garrison, after Marcus Aurelius under a consular legate, still with only one legion. The frontier on the Danube was protected by the establishment of the two colonies Aelia Mursia (Esse) and Aelia Aquincum (Alt-Ofen, modern Buda) by Hadrian. Under Diocletian a fourfold division. of the country was made.
The native settlements consisted of pagi (cantons) containing a number of vici (villages), the majority of the large towns being of Roman origin. The country was fairly productive, especially after the great forests had been cleared by Probus and Galerius. Before that time timber had been one of its most important exports. Its chief agricultural products were oats and barley, from which the inhabitants brewed a kind of beer named sabaea. Vines and olive trees were little cultivated. Pannonia was also famous for its breed of hunting dogs. Although no mention is made of its mineral wealth by the ancients, it is probable that it contained iron and silver mines. Its chief rivers were the Dravus (Drave), Savus (Save), and Arrabo (Raab), in addition to the Danuvius (less correctly, Danubius), into which the first three rivers flow.
The ancient name Pannonia is retained in the modern term Pannonian plain.