THE FRONTIER

Having considered society, economy and politics inside the western Roman Empire and amongst the barbarians, we now examine the inter-relationships of the two worlds. A number of issues require attention. The first is military: we must explore the nature of the Roman–barbarian frontier and that of the ‘barbarian threat’. Second, there are political issues: the barbarians' use by the Roman Empire and vice versa, and the interconnectedness of Roman and barbarian politics. Finally, we must consider the culture and identities of those barbarians who entered and lived within the Roman Empire.

During the mid-third-century political and military crises the Empire gave up several tracts of land. In the 260s it abandoned the agri decumates (Tithe Lands) between the upper Rhine and Danube and the Alamanni settled this area. In the next decade it abandoned Dacia, which was taken over by Sarmatians and Goths. At some time apparently in the early 280s the Romans withdrew to some extent from the southern part of MauretaniaTingitania, around Volubilis (Ksar Faraoun, Morocco).

In Britain the north of the province continued to be marked by Hadrian's Wall. Effective control may have shaded out as one approached the western highland regions, particularly in the mountains of Gwynedd, although there are traces of fourth-century occupation around the north Welsh coast and a new fort was constructed at Cardiff, perhaps against Irish raiding. In the south and east, from the late third century, a series of forts was constructed from the Wash to the Solent.