Probably the most valuable piece of information conveyed to us by Nennius, relating, it is true, rather to the history of Wales than to that of England, is derived from these same _Genealogiæ Regum_. It is to the effect that Maelgwn, King of Gwynedd (North Wales), was descended in the fifth degree from a certain Cunedag, who with eight sons marched southward from Manau Guotodin (which is identified with the district of Lothian), and drove “the Scots” from the region of Gwynedd, to which they never returned. This southward march took place, he says, 146 years before Maelgwn reigned. Now, Maelgwn, who was one of the five kings so fiercely denounced by Gildas, is a historical personage who certainly reigned in North Wales and whose death is dated in 547. He is also a link in the chain of Welsh kings who continued to reign so long as Wales had any independent rulers. The statement, therefore, amounts to this, that a little before 400, say in 380, or about the date of the usurpation of Maximus, a chieftain named Cunedag with his eight sons, and, doubtless, a large army, marched right across Britain from the Firth of Forth to the Menai Straits, drove out the “Scots,” that is the Irish invaders who were in possession of the country, and established a dynasty which endured for nine centuries (380–1283), till Llewelyn and David, the last royal descendants of Cunedag, were slain by the order of Edward Plantagenet. This is a fact unrelated to any other that has been handed down to us, but which suggests the reflection how many great movements of population, all memory of which has perished, may have been going forward in our island during these mist-covered fifth and sixth centuries of our era. Moreover, the fact that we have here apparently an instance of a Pictish king conducting a campaign of extermination against the “Scots,” though these Scots were in Wales, throws some doubt on the conventional theory that all the calamities of undefended Britain were due to a war in which the Picts and the Scots were acting in concert.