Pannonia (Byzantine province)

Byzantine Pannonia succeeded the name of much bigger classical Roman province of Pannonia. In other words, The Byzantine one covered only a small eastern part of ancient Roman Pannonia. In the 2nd century, the original Roman province was divided into two ones: Pannonia Inferior and Pannonia Superior. Subsequently, the area was subdivided into four provinces finally: Pannonia Prima, Pannonia Valeria, Pannonia Savia and Pannonia Secunda. Capital of Pannonia Secunda was Sirmium.

In the middle of the 5th century, the territory of former Roman Pannonia was ceded to the Huns by Theodosius II, and after the death of Attila it successively passed (entirely or partially) into the hands of the Ostrogoths, Lombards and Gepids.

A contract from 510 assigned most of the territory of former Roman Pannonia (including Sirmium) to the Ostrogoths, while the eastern part of present-day Syrmia (which included the city of Bassianae) was assigned to the Byzantine Empire. In 536, Sirmium was placed under the control of the Gepids. The Lombard–Gepid War (567) ended with a Lombard-Avar victory and annihilation of Gepids, while Sirmium was retaken by the Byzantine Empire.[1]

From 567 to 573, the Byzantine Empire was in a war with the Avars, who aimed to conquer Byzantine Pannonia. Temporary truce was declared in 573, but the war was resumed. Due to the fact that Byzantine-Persian war also started in this time, the Byzantine Empire was not able to defend Pannonia. The city of Sirmium was finally conquered by the Avars in 582, thus marking end of Roman control of Pannonia since Classical Antiquity.

The Byzantine Empire re-established control over Pannonia in the 11th century, leading to the creation of the Theme of Sirmium to administer the region, but not lasting long.