In the shadowy traditions of the Welsh bards we hear of a certain Ossa Cyllelawr or Ossa the Knife-man, who is spoken of as a great antagonist of Arthur, and who appears to be a genuine progenitor of the Bernician kings. It is apparently his son Eobba who bears the terrible title, “The Great Burner of Towns,” which is generally given to the next link in the pedigree, Ida, King of Bernicia. Here, at last, we are on firmer historical ground, for this is that Ida of whom we read in the Chronicle (here quoting Bede) that “he began to reign in 547, and that from him sprang the royal line of Northumbria,” that “he reigned twelve years, and that he built Bebbanburh [Bamburgh], which was at first surrounded by a hedge and thereafter with a wall”.[54] Notwithstanding the comparative shortness of his reign, Bernician Ida from his rock-fortress of Bamburgh evidently wielded a mighty power, and we are probably right in attributing to him the first great extension and consolidation of the Anglian power between the Tees and the Firth of Forth. He had twelve sons, six of whom followed him in rather quick succession during the last half of the sixth century. We have no hint of civil war or domestic treason, and it is therefore reasonable to suppose that many of these warlike kings fell in battle with their Celtic neighbours in the west. This is indeed hinted by the scanty notices in Nennius’s history. We appear to be justified in speaking of Ida as king of Northumbria, though that may not have been the title given to him by his contemporaries, for it seems to be the outcome of the very confused notices in Nennius’s _Historia Brittonum_ that Deira as well as Bernicia was subject to his sway. But on the death of Ida (560), if we may trust the Chronicle, a prince of another line claiming descent from Woden through eleven generations of mortal men, Aelle or Ella, began to reign over the southern kingdom, Deira, and reigned for twenty-eight years. Were the relations between the two dissevered kingdoms friendly or hostile? It is impossible to say. The presence of the Deiran slave boys in the Roman forum suggests the latter hypothesis; the fact that Acha, the daughter of Aelle, was married to Ethelfrid of Bernicia suggests the former. Possibly a war between the two Anglian kingdoms had been followed by peace and a matrimonial alliance. However this may be, on the death of Aelle in 588, Ethelric of Bernicia, son of Ida, succeeded--assuredly not peaceably--to the throne of Deira, which, after five years of reigning, he handed on together with his ancestral kingdom to his son Ethelfrid.