The course of development will be more clearly followed if it is stated in summary beforehand. The hostile relations between Ulster and Connacht continued, but the kings of Connacht grew gradually more powerful. They extended their power step by step over central-eastern Ireland, the ancient Fifth of North Leinster, and then step by step over all Ulster except what is now comprised in the counties of Down and Antrim. Upon the increase of power thus acquired they established a hegemony or primacy over all Ireland. This primacy found its definite expression in the institution of the high-kingship or Monarchy. The first stage in the process was the occupation of Uisneach by Tuathal Teachtmhar. Who was this Tuathal? According to the genealogies he was sixth in descent from Eochu Feidlech, who was the father of Medb, queen of Connacht. Accepting Medb's date as fixed or estimated by all our ancient writers, she flourished just at the commencement of the Christian Era. Tuathal was five generations later, and from dated Irish pedigrees we can calculate an average of almost exactly three generations to a century. Tuathal therefore would have flourished in the third quarter of the second century, say between A.D. 150 and A.D. 175. Exact dates are assigned to him in the extant regnal lists, but these lists do not agree with each other, and it is safer to rely on the law of averages. Tuathal, we are told, set up a new kingdom for himself around Uisneach. The territory surrounding Uisneach was part of the old Fifth of North Leinster. Consequently the alliance of the Four Great Fifths against Ulster was no longer operative. Tuathal was a prince of the Connacht dynasty, and his occupation of Uisneach was an invasion of North Leinster and the first stage in the break-up of the Pentarchy. With regard to Tuathal we are told that before his birth the Rent-paying tribes throughout Ireland revolted against the Gaelic ascendancy and overthrew it. Tuathal's mother fled to Britain and in Britain he was born. By the time he came of age the revolution had spent its force and a reaction set in. Tuathal returned to Ireland, by some he was welcomed, others he overcame by force, and he became the strongest king in Ireland. It was then that he took possession of Uisneach.