Early Scandinavian Dublin
In the year 795 Vikings (probably of Norwegian origin) raided islands off the coast of Ireland for the first time. This was the beginning of a new phase of Irish history, which saw many native communities – particularly ecclesiastical ones – relocate themselves on the continent, or further afield in places like Iceland and the Faroe Islands, to escape the pagan marauders. For about two decades the invaders confined their activities to coastal settlements; raiding parties were generally small and there is no evidence that any of them wintered in Ireland during this early phase of "hit-and-run" activity. Typically the Vikings would arrive at a settlement without warning, plunder what goods and people they could – the people were usually sold as slaves, though notable personages were often held for ransom – before retreating to their Scandinavian or British bases. This period lasted from 795 until 813, after which there occurred a hiatus of eight years.
It is now thought that these early raids were launched directly from southwest Norway, and that during the period of calm (814–820) the Norwegian Vikings were occupied in northern Britain, laying the foundations of a new kingdom referred to in Irish sources as Laithlind (later Lochlainn). Laithlind was once thought to be in Norway but it is now identified with Viking settlements in the British Isles, especially those in Scotland and the Isle of Man.
Viking Age
The first Viking raids began between 790 and 800 along the coasts of western France. They were carried out primarily in the summer, as the Vikings wintered in Scandinavia. Several coastal areas were lost to Francia during the reign of Louis the Pious (814–840). But the Vikings took advantage of the quarrels in the royal family caused after the death of Louis the Pious to settle their first colony in the south-west (Gascony) of the kingdom of Francia, which was more or less abandoned by the Frankish kings after their two defeats at Roncevaux. The incursions in 841 caused severe damage to Rouen and Jumièges. The Viking attackers sought to capture the treasures stored at monasteries, easy prey given the monks' lack of defensive capacity. In 845 an expedition up the Seine reached Paris. The presence of Carolingian "deniers" of "ca" 847, found in 1871 among a hoard at Mullaghboden, County Limerick, where coins were neither minted nor normally used in trade, probably represents booty from the raids of 843–846. After 851, Vikings began to stay in the lower Seine valley for the winter. Twice more in the 860s Vikings rowed to Paris, leaving only when they acquired sufficient loot or bribes from the Carolingian rulers.