Though Ireland was never properly a part of the Roman Empire, it was a part of the Roman frontier. The extent of exchange and interaction with Britain and the Continent justifies our consideration of Ireland in the context of Late Antiquity as early as the third century CE. Elva Johnston has noted that the fifth century has served as ‘a chronological boundary’ and, as a result, ‘early Irish historical scholarship is greatly invested in analyzing conversion, Christianization and changing religious affiliations’, rarely treating the earlier period. Johnston has challenged the tendency of Irish historians to view Ireland as isolated from the Roman world and has argued that it should be viewed in a comparative context and as a frontier of the Empire. She writes of Roman frontiers that ‘They are no longer viewed as lines on a map, as hard borders defended by large-scale fortifications … instead they are seen as zones of complex cultural, economic, and military interaction’. The influence and reception of Roman, Gallo-Roman, and Romano-British culture along Irish transmarine frontier zones is witnessed in the archaeological record and includes decoration, ornament, and, of greatest significance to the current study, literacy, ogham being the primary example.

It is clear now that Christianity and its literate culture arrived in Ireland at an early date, likely by way of Roman Britain. The Romans had arrived in what they would call the Roman province of Britannia as early as 55 or 54 BCE, as Julius Caesar reports in his Gallic Wars. However, the Roman presence would not endure until 43 CE when Roman emperor Claudius, in front of 200,000 soldiers, invaded the island from the south. The Romans would gradually take control of much of Britain over the coming decades. The Roman presence in Britain was naturally to spread to the near neighbours in Ireland.

The archaeological evidence shows that the Irish were involved in maritime trade with Romano-British and Spanish traders, and perhaps even traders from the Mediterranean world, as early as the later fourth or early fifth century CE. Burials in the Roman fashion, found scattered along the eastern coastal region, provide evidence that Romans may have resided in Ireland as early as the first or second century CE.