The succession to these several grades of _Ri_ or king was the same as that of the _Ri Tuath_, and was regulated by the law of Tanistry, that is, hereditary in the family but elective in the individual, the senior of the family being usually preferred; but as, when the king was chosen, the Tanist would naturally be selected from the next most powerful branch of the family, it fell at length into an alternate succession between the two most powerful branches. This becomes at once apparent when we examine the actual succession of these kings as recorded in the Annals. The sovereignty over the whole of Ireland fell for several centuries into one branch of the great family called the Northern Hy Neill, and the throne was filled alternately from two branches of it. The succession of the kings of Munster shows the same peculiarity of an alternate succession between the descendants of two sons of the mythic founder of that kingdom, and furnished the illustration upon which a Dissertation on the Law of Tanistry, attributed to General Vallancey, but really written by Doctor John O’Brien, Bishop of Cloyne, was founded. The province of Ulster, where an ancient Pictish population was encroached upon and gradually superseded by Scottish tribes, exhibits the remarkable peculiarity of an alternate succession of the kings of Ulster between a family descended from its old Pictish kings and one of the earliest colonies of Scots, that of the _Dalfiatach_, who settled among them.[171] [Sidenote: Connection between superiors and dependants.]