The village of Dubh Linn (in Old Irish) can be dated to the pre-Roman prehistoric era in Ireland. A monastic center also developed nearby, within the province (and kingdom) of Leinster.
In 851 AD a fleet of Dubgeinte (Danish Vikings) arrived in Dublin, most probably from England; they attacked the Finngaill (Norwegian Vikings settled in Ireland) and they plundered the naval encampment of Dublin.
In 853 AD ‘Amlaíb, son of the king of Laithlind, came to Ireland and the Foreigners of Ireland submitted to him and he received tribute from the Irish’.
The Viking or Norse kingdom of Dublin was repeatedly attacked by the Irish kings. The mid ninth-century Irish attack was violent and successful, and Viking invaders who failed in Munster in the early tenth century succeeded readily in York. Several major Irish kings fell in battle against the Vikings—Niall Glúndub (919), king of Tara; Muirchertach (943), king of the North; Ruaidrí ua Canannáin (950), claimant to the kingship of Tara; Congalach Cnogba (956), king of Tara; Brian (1014), king of Ireland21—but few Anglo-Saxon or Scottish kings did.
Four Uí Ímair kings ruled in the Irish Sea region and made the kingdom of Dublin their principal seat of power during this period: Glúniairn (d. 989), Sitric Silkenbeard (d. 1042), Ívarr Haraldsson (d. 1054), and Echmarcach mac Ragnaill (d. 1064).
As a ruler of Dublin, kings came to bear the Irish title ‘rí Gall’ (King of the Foreigners), which remained the reserve of the Scandinavian dynasty of Ívarr (henceforth referred to by its Irish equivalent ‘Uí Ímair’) until 1054.
Between 1169 – 1171 the Normans of England invade Ireland, and Viking Dublin and Waterford are conquered, never to regain independence. Hasculf Thorgillsson attempts to regain it by force but is killed in the process.
Norse Kingdom of Dublin
