Introduction

In the earlier, i.e. Hellenistic and Late Republican, periods the Danube and Balkan area had merely formed a backyard of Italy in the west and of the Greek polis-centred world in the east, but in the course of the 1st and 2nd centuries AD it developed into the backbone of the Imperium Romanum. Thanks to its military and human resources, the region made a vital contribution to the survival of the Empire at the time of the 3rd century crisis. One of the results of this comprehensive process was the transformation of the former periphery of the Danube into a core area of the Empire. During the 3rd century AD a new imperial elite evolved from the military class of the Danube and Balkan provinces. This elite not only inherited but renewed Rome’s ideology and reshaped its ruling mechanisms. Two of the most prominent representatives of this social group are Diocletian and Constantine. From this perspective, the Danube and Balkan area may be regarded as a key region for a deeper understanding of several fundamental processes which shaped Roman imperial history: first the implementation of Roman rule and government, second the interaction and ultimately reversal of roles of the Empire’s centre, Italy, and its peripheral zones