From a very early period the whole of the islands along the western coasts of Scotland were favourite resorts of the Scandinavian Vikings, who established themselves amongst the scanty population of the Hebrides with far greater ease than upon the mainland. From the intermixture of the natives with the northern invaders, sprung the race to which the Irish annalists, and occasionally the Sagas, give the name of Gallgael, a horde of pirates plundering on their own account, and under their own leaders, when they were not following the banner of any of the greater sea-kings, whose fleets were powerful enough to sweep the western seas, and exact tribute from the lesser island chieftains. Man was from an early period the seat of the sovereignty of the Isles, which was long centred in the family of the Hy Ivar, lords of Dublin, and often kings or Jarls of Danish Northumbria. In the middle of the tenth century the Islands fell under the dominion of Eric Blodæxe, whose rivalry with Olave Sitricson weakened and divided the power of the Anglo Northmen; and after the death of Eric they were ruled by Magnus Haraldson and his family, the representatives of the elder Sitric, who appear to have been driven from Limerick, the early seat of that branch of the Hy Ivar. The exploits of this line of princes upon the coasts of Wales are continually to be met with in the Welsh and Irish chronicles of the period, but their title of Oirrigh is a proof that they were not independent, and they probably paid tribute to the head of their family at Dublin. The united power of the Orkneys, the Islands, and the western coasts of Scotland, in addition to the Irish Norsemen, failed to avert the catastrophe of Clontarf, [Sidenote: A. D. 1014.] and the eleventh century opened upon the decline of the Hy Ivar. The personal energy of Thorfin, the great accession of territory resulting from his connection with Malcolm the Second, and the union of all the northern islands with his wide possessions on the mainland, enabled him to take advantage of their weakness; and if the Sagas are correct, in attributing to him a large _Riki_ in Ireland, and in extending his dominion from Thurso Skerrey to Dublin, the Jarl of the Orkneys may have assumed the prerogatives of the earlier kings of Dublin, exacted tribute from their dependants, and become the acknowledged leader of the Scottish and Irish Northmen. During the ascendancy of Thorfin the Islands were for some time under the rule of a certain Gille, and of Suibne MacKenneth, [Sidenote: A. D. 1034.] names pointing to the Gaelic element amongst the Gallgael; and it is not unlikely that they owed their rise to the Jarl, and were amongst the earliest of the mainland chiefs of the Oirir-Gael who disputed the possessions of the Hebrides with the kings of Man.[192]