Balkan Campaign: The Avars lift the siege at the Byzantine stronghold of Tomis. Their leader Bayan I retreats north of the Danube River after the Avaro-Slavic hordes are decimated by the plague.
Bayan I reigned as the first khagan of the Avar Khaganate between 562 and 602.
As the Gktrk Empire expanded westwards on the Eurasian Steppe during the 6th century, peoples such as the Avars (also known as the Pseudo-Avars, Obri, Abaroi and Varchonites) and the Bulgars migrated into Central Europe and the Balkans. Bayan I led the Avars (along with some Bulgars) into Pannonia, where they established their khaganate from 568.
Maurice's Balkan campaigns were a series of military expeditions conducted by Roman Emperor Maurice (reigned 582–602) in an attempt to defend the Balkan provinces of the Roman Empire from the Avars and the South Slavs. Maurice was the only East Roman emperor, other than Anastasius I, who did his best to implement determined Balkan policies during Late Antiquity by paying adequate attention to the safety of the northern frontier against barbarian incursions. During the second half of his reign, the Balkan campaigns were the main focus of Maurice's foreign policies, as a favourable peace treaty with Persian Empire in 591 enabled him to shift his experienced troops from the Persian front to the region. The refocusing of Roman efforts soon paid off: the frequent Roman failures before 591 were succeeded by a string of successes afterwards.
Although it is widely believed that his campaigns were only a token measure and that Roman rule over the Balkans collapsed immediately after his overthrow in 602, Maurice was actually well on his way to forestalling the Slavic landfall on the Balkans and nearly preserved the order of Late Antiquity there. His success was undone only over ten years after his overthrow.
Retrospectively, the campaigns were the last in the series of classical Roman campaigns against the Barbarians on the Rhine and Danube, effectively delaying Slavic landfall on the Balkans by two decades. With respect to the Slavs, the campaigns had the typical trait of Roman campaigns against unorganized tribes and of what is now called asymmetric warfare.