Four Tribes of Tara

The Four Tribes of Tara was an alliance of powerful clans that consisted of the O'Harts, O'Kelly's, O'Connolly, and the O'Regan. The princes of Tara were also styled princes of Bregia, to and contained the districts about Tara, Trim, Navan, Athboy, part of Dublin north of the Liffey. The Four Tribes were major defenders of Ireland against Viking invasions during the 8th and 9th centuries.