[1] It lies at the western shore of Lake Beloslav in the northeastern end of the Devnya Valley and along the southern slopes of the Dobruja Plateau, in the close proximity to the Black Sea.

Under Emperor Diocletian Marcianopolis became the centre of the province Moesia Secunda of the Diocese of Thrace, and was rebuilt thoroughly in the late 3rd and early 4th century.

During Emperor Valens' conflict with the Goths (366–369), Marcianopolis was a temporary capital of the empire and the largest city of Thrace according to a source from the period.

Despite the regular barbarian attacks, Marcianopolis remained an important centre until an Avar raid finally destroyed it in 614–615, although it still continued to be mentioned in maps until much later.

As the Slavs settled in the Balkans in the 7th century they called the ruins of the ancient city Devina, from Proto-Indo-European *dhew-(i)na or *dhew-eina ("spring, source, stream, current") through Thracian, but associated with Slavic deva ("virgin").

The lower river Devnya was a traditional industrial centre since Ottoman times with numerous watermills serving much or riverless Southern Dobruja, a breadbasket area.