As early as the introduction of Christianity Ireland was already divided into four such aggregations of tribes--kingdoms they are commonly called--answering pretty nearly to the present four provinces, with the addition of Meath, which was the appanage of the house of Ulster, and included West Meath, Longford, and a fragment of the King's County. Of the other four provinces, Connaught acknowledged the rule of the O'Connors, Munster that of the O'Briens, Leinster of the McMurroughs, and Ulster of the O'Neills, who were also in theory over-kings, or, as the native word was, Ard-Reaghs of the entire island.