Avar–Byzantine wars
The Avar–Byzantine wars were a series of conflicts between the Byzantine Empire and the Avar Khaganate. The conflicts were initiated in 568, after the Avars arrived in Pannonia, and claimed all the former land of the Gepids and Lombards as their own. This led to an unsuccessful attempt to seize the city of Sirmium from Byzantium, which had previously retaken it from the Gepids. Most subsequent conflicts came as a result of raids by the Avars, or their subject Slavs, into the Balkan provinces of the Byzantine Empire. The Avars usually raided the Balkans when the Byzantine Empire was distracted elsewhere, typically in its frequent wars with the Sassanid Empire in the East.