The Ireland of Cormac's time was divided into small kingdoms or "túatha," perhaps 150 in all, on average around 500 square kilometres in area, with a population of some 3000 each. In theory, but not in practice, each "tuath" had its own king, bishop, and court. Variations in size and power were very considerable. Groups of "tuatha" were dominated by one of their number, whose king was their collective ruler. Above these stood the five great provincial kingships whose names survive in the provinces of Ireland: Connacht, Leinster, Ulster, Meath, and Cormac's Munster. To these can be added the kings of the northern and southern Uí Néill. These last provided were the High Kings of Ireland, kings whose authority was an increasingly obvious political fact in Ireland of the 8th and 9th centuries. In Cormac's time the High Kingship was held by Flann Sinna of the Clann Cholmáin branch of the southern Uí Néill. In addition to these native Irish kings, Ireland had also seen Scandinavian and Norse-Gael kings establish themselves along the coasts during the Viking Age. The destruction of Viking settlements on the northern coasts by Flann's predecessor Áed Findliath, followed by much internal dissension, had weakened the Vikings, who were expelled from Dublin by Flann's allies in the year that Cormac became the king of Munster.