With regard to Dublin, however, the case is quite different. The series of kings there from the year 853 until about 1200, and consequently for almost three centuries and a half, is pretty complete. It was a natural consequence of the considerable power and influence possessed by the kings of Dublin, that their names were often mentioned in the chronicles in connection with important events both in Ireland and in the neighbouring countries. The Norwegian kings in Dublin knew how gradually to strengthen and extend their power, not only by arms, but also by a shrewd and able policy. They soon learnt how to avail themselves of the intestine disputes by which the Irish tribes and chiefs were divided. They joined one of the ruling parties, contracted marriage with the daughters of Irish kings and chieftains, and on their side gave Scandinavian women in wedlock to leading Irishmen. According to the old Irish book called “the Book of Lecan,” the Irish king Congolaich (934-954) had a son, Mortogh, by Radnalt, daughter of the Dublin king Anlaf, or Olaf. At a somewhat later period a Norwegian king in Dublin, named Anlaf, was married to an Irish woman, Dunlath, who was mother of the Dublin king “Gluin-Jarainn” (Iron-Knee). Similar marriages between Norwegian and Irish royal families are often mentioned; even King Brian Boru, so adored by the Irish, was nearly related to the Norwegian kings. He was father of Teige and Donogh, by Gormlaith, or Kormlöd, a daughter of Morogh Mac Finn, king of Leinster. But Gormlaith was also married for a long time to the Dublin king, Anlaf, by whom she had a son, afterwards the celebrated king of Dublin, Sigtryg Silkeskjæg (Silk-beard); and thus Brian Boru’s two sons Teige and Donogh—of whom Teige afterwards married Mor, a daughter of the “Danish” king Eachmargach of Dublin—were half-brothers of their father’s enemy, King Sigtryg. “The Book of Leinster” says that Gormlaith was likewise mother of the Norwegian-Irish king Amlaff Cuaran (Olaf Kvaran); whilst the Irish chronicler, Duald Mac Firbis, mentions this same Olaf Kvaran as married to Sadhbh (Save), a daughter of Brian Boru, and that even “at the time when the battle of Clontarf took place.” After this we are better able to understand how it happened that whole Irish tribes, with their kings at their head, so often fought in union with the Norwegians and Danes; since we learn that their mutual political interests were hound closer together by the ties of relationship.