One of my favorite research books for The Last Abbot of Linn Duachaill was Nancy Edwards’ The Archaeology of Early Medieval Ireland (Routledge, 1996).
Chapter One is “The Roman Impact,” a topic which can seem perplexing at first. After all, Ireland was never part of the Roman Empire. How can there even be a Roman impact on early medieval Ireland?
As it happens, there was, but given the location of Roman finds, contact was probably limited to coastal trading areas, largely the greater Dublin area. Most Roman-era finds have been between the Boyne river and the Wicklow mountains. In all likelihood, the contact was not directly with Rome, but with Roman outposts in Britain and Gaul.
It’s worth remembering that even before the appearance of the Vikings, the Irish Sea was crossed regularly by Irish and Welsh sailors. Saint Patrick was actually a Welsh boy captured by Irish raiders and taken back to Ireland as a slave. The coastal areas of what we think of as separate nations might well have had more contact with one another than either did with the inland areas of their own country.
Edwards makes the point that despite the comparative rarity of Roman-era artefacts in Ireland, they are important because they demonstrate that even before the ‘official’ beginning of early medieval Ireland, change is in the wind. By the 5th c, Ogham inscriptions show that literacy is coming to Ireland; changes in pollen survival suggest that the heavier Roman plough has arrived. We see Roman influence as well in the design of Irish swords and glass-making techniques.
Ireland was never part of the Roman Empire, but from the late Roman / early medieval period, Rome was a thought influence on the Irish, a reality which we reflected in Last Abbot.