600-1169 CE
From 600 to 1169 CE, the Gaels built a civilization of saints and scholars on the edge of the known world — their monasteries preserving Latin learning while Europe burned, their monks carrying the gospel from Iona to the courts of Frankish kings. High kings rose and fell at Tara, Viking longships brought terror and then trade, and Brian Boru broke Norse power at Clontarf — until Norman knights rode into a land that had never known cavalry warfare.