An invitation to speak to the Offaly Historical Society on 22 February 2018 caused me to consider whether or not you could tell the history of early medieval Ireland by concentrating on just one county. In the case of Offaly it proved possible.
When written Irish history begins (certainly by the late fifth century) Ireland was a complex patchwork of political units unified by the Celtic language. This Irish speaking culture came to Ireland before 700 along with the use of Iron and other Celtic traditions. A second wave of Celts from central Europe arrived on the island around 300 BC. These were the people that introduced La Tène artistic styles into Ireland.
Much of what we know about these people comes from the discovery of Old Croghan Man in 2003. Found in Offaly near the Meath border, this poor devil was sacrificed sometime around 270 BC. His nipples were sliced as part of the ritual associated with his murder and, tellingly, he wore a bracelet with a La Tène decoration. This is the world that Patrick describes in his Confessio written towards the end of the 400s AD: a world of strange pagan rituals and sun worship.