By 562, the Avars and Bulgars had reached the Lower Danube: it was most likely in that year that Bayan became their supreme Khagan, as his predecessor, the Kutrigur khan Zabergan had died.
As allies of the

After ten years of uneasy, undocumented peace, Bayan again marched against Sirmium, wresting it from Byzantine hands after a two-year siege, then took also Singidunum, evicting the Byzantines from the inner Balkans and opening the area to an unstoppable influx of