When we come to St. Patrick's time, the fifth century, we feel ourselves within the scope of clear and definite written records. These ancient boundaries are for the most part only memories. There is no longer a Pentarchy but a Heptarchy, which remains substantially unchanged for several centuries and is described in detail by the Book of Rights, compiled about the year 900 and revised about a century later.
In this new arrangement, Munster has its present extent plus the southern angle of King's County. Connacht has lost County Clare, but has annexed territory east of the Shannon as far as Loch Erne and Loch Ramor in County Cavan. This territory has been taken from Ulster, which no longer exists as a political unit, but is divided into three of the seven chief kingdoms. These are the kingdom of Ailech on the west, the kingdom of Ulaidh on the east, and the kingdom of Airgialla or Oriel in the middle. The Fifth of North Leinster has ceased to be a kingdom. There is only one kingdom of Leinster, which extends as far north as Dublin, the river Liffey and its tributary the Rye, which runs by Maynooth. This kingdom contains what remains of North and South Leinster and is ruled by the ancient dynasty of South Leinster.
The seventh chief realm is that of Meath which has been formed from parts of North Leinster and of Ulster. Its northern boundary is nearly but not quite the same as the present northern boundary of Leinster. It takes in part of County Cavan and excludes the northern part of County Louth, north of Ardee.
The strictly historical period in Ireland begins with St. Patrick. The authentic writings of St. Patrick are the earliest written documents of Irish history. But I do not think it would be just to say that all before that time is prehistoric. If all we had for the first four centuries of the Christian Era was a slender thread of narrative like Livy's story of ancient Rome, we might wonder how much profit, if any, could come from examining it. We are not in so poor a case. We have a substantial mass of traditions, connected and disconnected, which, I think, enable us to supply the void of written documents in a manner that will carry conviction.
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.
I had become familiar with this plan of transforming pedigrees into regnal lists before I first read Buchanan's history of Scotland. In that book I found a list of forty-three kings who reigned over Scotland before Fergus of Dal Riada went over from Ireland. All the names seemed strange. They were apparently Latinised from some other language, the history being written in Latin. Were they invented, like the names in "Gulliver's Travels," or, if not, where were they found? Can it be, I asked myself, that the Scottish historians, like the Irish, filled the vacuum out of pedigrees? And if so, out of what pedigrees? Now it is a matter of historical record that, on the inauguration of a king of Scotland, a part of the ceremony consisted in the recitation of his pedigree, and this custom was kept up until the Dal Riada line died out with Alexander III in 1285. Therefore, I argued, the pedigree most familiar to an early Scottish historian was that of the kings of Dal Riada. I turned up this pedigree in the Irish genealogies and my conjecture was confirmed. Scotland and Ireland are all along agreed that Fergus MacEirc, an Irish prince, settled in Scotland and founded there a new kingdom and dynasty. But the forty-three kings of Scotland named before Fergus are nevertheless the forty-three ancestors of Fergus, from father to son, in the Irish genealogy. The list comprises names so well known in Irish story as Ederscél, that Munster king, whose death is said to account for the forfeiture of Leinster territory to Munster; his son Conaire Mór, whose tragic fate is told in the story of Da Derga's Hostel; and the younger Conaire, son of Mugh Lámha, who also figures in the Irish hero-lore. All these and their forefathers, up to the eponymous Iar, head of the Ivernian stock, figure one after another in the artificial history of the first Scottish dynasty beyond the sea.
Let us get away then from such unprofitable material and let us see what comes to us in the guise of traditions of substance. We start off from the Pentarchy and the Ulster cycle. The Ulster stories have for their main basis the hostile relations between Ulster and Connacht. Being Ulster stories, they do not prolong their scope beyond a time in which Ulster has generally the best of it. Ulster's mishaps merely serve to heighten the effect, which is Ulster's heroism and victory. It was when this time of glory was but a memory, when Emain was a deserted site and the remnant of the Ulaidh occupied only a tiny fraction of their former territory, that these stories took their present shape and were committed to writing. We have to turn to another set of traditions, to those connected with the monarchical kindred of historical time, to learn how things developed from the stage depicted in the Ulster tales.