The period in question begins with the solid background of the Pentarchy. It ends with the solid foreground of the Christian Heptarchy. The problem before the student is not merely to fill up the intervening space with a random collection of traditional material, but to find out by what stages and through what causes the transformation took place; how a central monarchy came into being; how Ulster was broken up into three distinct realms; how Leinster contracted from two great kingdoms into one; how the new and powerful kingdom of Meath was established; and how Munster grew to about twice its ancient extent. Our old native historians did not concern themselves with accounting for anything. Their chief model was Eusebius, and Eusebius was content to give lists of kings with the length of each king's reign as the sole history of various realms of antiquity throughout centuries. So the only consecutive history we find of Ireland before St. Patrick's time consists in like manner of regnal lists with little bits of anecdotal matter added here and there. Even these regnal lists are not authentic. They are made up artificially from pedigrees, and I have already shown that the method was so recklessly artificial as to make a king out of a misread note to one of the pedigrees. Even the oldest written history of Ireland extant follows this method. It does not indeed extend the Irish monarchy back to the Gaelic invasion. It declares the authentic history of Ireland to begin with the foundation of Emain Macha, dated 305 B.C., and it begins the Tara monarchy in A.D. 46. But from this date onward it gives the succession of the high-kings, and that succession is one of a kind unknown in the historical period. It is a succession from father to son, which is contrary to the known custom of all the insular Celts, in Ireland, Wales, and Scotland. In other words, it is again merely a pedigree converted into a dynastic succession. When a single pedigree is utilised in this way, the fact is easily discovered. Later historians adopted a less obvious artifice, and one at the same time which made their account more widely acceptable. They shortened the reigns of the kings in the earlier history so as to leave gaps between them, and into these gaps they inserted names from other pedigrees besides that of the Tara monarchs. They took these names in turn from the genealogies of the kings of Munster, Leinster, Oriel, etc., and thus, by giving every part of Ireland a share in the monarchy, they produced a regnal history which was flattering in an all-round way and which succeeded in relegating the earlier device to comparative oblivion.