The province of Macedonia played an important role in the transition of the ancient world to the world of Christianity, for it formed the immediate hinterland of the Danubian Roman frontier, which bordered upon the barbarian world. Successive barbarian tribes that crossed the Danube (Alamanoi, Sarmatai, Visigoths, Ostrogoths, and Huns) plundered and wrought extensive destruction during the 4th and 5th centuries.
General view of the city
The administrative changes effected by Constantine the Great and Justinian I were designed to bring about an improved organisation of the state and more effective resistance to the raiders through the construction of a series of defence works and new fortresses.
The simultaneous spread and prevalence of Christianity and its establishment in 380 as the official religion of the state reshaped the Roman Empire: in 395 it was divided into two parts, of which the western was of short duration (it was disbanded in 476). At the same time the Church acquired a full organisation, while orthodox dogma was clearly defined by Ecumenical Councils and heresies were suppressed.