The
Romans
became the dominant power in the region after their defeat of Macedonia in 168 BC, but it took almost two centuries for the empire to subdue the Thracians, who were in constant revolt. It wasn't until about 50 AD that the conquerors were finally able to carve out secure administrative units, creating the province of
Thrace
to the south of the Balkan range and
Moesia
to the north. Using slave labour, the Romans built garrisons, towns, roads and bridges across their domain, and conscripted many Thracians into their legions.
Military strongholds and neighbouring civilian settlements sprang up along the
Danube frontier
(relics of which can today be seen in the museums of Vidin, Pleven and Sofia), while prosperous new towns like
Nicopolis ad Istrum
(near Veliko Tārnovo) commanded the trade routes inland. Many of the old Greek towns along the coast continued to thrive, and although they now hosted a population of mixed Greek and Thracian descent, Greek language and culture remained dominant throughout the region.
From the third century onwards the empire's contraction and decline was hastened by recurrent invasions of the Danubian provinces by the Goths (238-48), Visigoths (378), Huns (447) and other so-called
barbarians
- civilization in Moesia and Thrace suffered greatly as a result. However, the division of the empire into two parts, with
Byzantium
inheriting the mantle of Rome in the east, meant that the authorities in nearby Constantinople could (for a while at least) concentrate their military resources more effectively here.
Both the Danubian frontier and the stronghold of Thrace were reinforced by Emperor
Justinian
in the sixth century, allowing urban life in the region a brief reprieve. Both Philippopolis (Plovdiv) and
Serdica
(Sofia) flourished during his reign. Even under Justinian, however, the
sklaveni
(ancestors of the Balkan Slavs) found a way of breaching the empire's defences, and indulged in big looting trips into Thrace in the 540s. By the seventh century, increasing numbers of Avars and
Slavs
were crossing the river with impunity, leaving the Byzantines with little choice but to allow them to settle and employ them as irregular frontier troops.
