Ethelred the Pious
"When the age of the Vikings came to a close, they must have sensed it. Probably, they gathered together one evening, slapped each other on the back and said, 'Hey, good job.'" -- from "Deep Thoughts" by Hans Håndi
The era of the Viking raids in Western Europe began in the late Eighth century and continued throughout the Ninth, Tenth, Eleventh, and Twelfth Centuries. The era of raiding extended for a very long time - a good deal longer than in, for example, our timeline.
The continued widespread practice of paganism was largely to blame for this. For one thing, there was less of a moral check on rape, pillage, and plunder for their own sake. The enslavement of Christian neighbors remained acceptable, profitable and widespread. And the persistent practice of concubinage on a large scale meant that every king, jarl, and lord in England had a host of sons with no land but plenty of ambition. In in the British Isles and the coastlands of Europe, they sought land and fortunes.
The unstable zones of fighting were used as a sort of proving ground for Danish and especially Norwegian leaders. Many future kings of Norway spent their youth based in England and fighting in Ireland, France, or Spain.
Some areas were closed to the Vikings. Some English tried to attack mainland Scandinavia, but it was difficult for raiding parties to unseat established and prosperous Viking rulers. The northern Celtic kingdoms of Alba and Strathclyde (united under one king after 943) were perennially allied with one or another of the Scandinavian rulers; while many a Viking launched an attack on northern Britain, it was dangerous to risk provoking their allies.
Northern Gaul was largely blocked as a Viking target after 925, when the Western emperor granted the March of Angelania (Anguèlènie) to the Anglo-Norse chieftain Sigtryggr the Squinty, in exchange for his defending the northern coast. A scion of the deposed rulers of Østangeln, Sigtrygg and his descendants kept the coast reasonably protected during the later tenth and eleventh centuries. However, the western coast, facing the Atlantic, remained vulnerable. Bordeaux fell to Viking bands in 938 and 960. It was recaptured by the Franks, but a Scandinavian settlement remained in the town. After 1000, when the Kingdom of Aquitania broke up, the Norse took over the town and the surrounding area, creating an independent maritime state. Around this time many began converting to Islam; eventually their state was made a vassal of the emirs of Nawar (Navarre).
Ireland was to suffer the worst of Anglo-Nordic restlessness. By 1000 the island was dotted with petty kingdoms and jarldoms. The strongest Norse state remained at Dyflin (Dublin), which from time to time was united with other Viking possessions in the Suð-ejar (South Islands, i.e. Man and the Hebrides), Ongellsey, and Østangeln in England. Others went to Iceland in the hopes of finding open land, fighting with the Norse already there. The early history of Iceland was therefore more turbulent than in OTL, and the establishment of the council called the Althing was delayed several years. However, Iceland was also left with a larger population and closer ties to the rest of Scandinavia, particularly England.
English Norse also raided the coasts of Spain. The Kingdoms of Navarre and Leon-Asturias were devastated by wars on two fronts, against the Norse and the Moors. The Norse invaders established a string of small states in the northern mountains, mostly in vassalage to the Umayyad Caliph at Cordoba. In 985 the Caliph burned Barcelona in the Spanish March, the last major Christian state to resist Moorish expansion.
Most of the Norse settlers in Spain would convert to Christianity or Islam. The small Norse territory in Galicia became the Christian Kingdom of Sant Jakob, or Santiago, while Norse Pamplona became the core of the later Vasco-Moorish kingdom.