What people provided the most serious challenge to Byzantine authority in the Balkan peninsula?

Answer 1

The most serious challenge to Byzantine authority in the Balkan Peninsula came from the Slavic peoples, particularly during the 6th and 7th centuries. The Slavs migrated into the region, establishing their own settlements and political structures, which undermined Byzantine control. Additionally, the rise of the Bulgarian Empire in the late 7th century posed a significant military threat, leading to conflicts that further weakened Byzantine influence in the area. This combination of Slavic migration and the emergence of powerful local states significantly altered the balance of power in the Balkans.