Throughout the Viking Age, virtually all the regions along Europe's western coastline and numerous towns situated along major rivers leading into the continent fell victim to Viking plundering.
The onset of Viking raids on the Frankish Empire can be traced back to 820, and by 834, these attacks had become a recurring occurrence for an entire generation. The Vikings targeted nearly every city and town in the Frankish Empire within their reach, including prominent centers like Rouen, Quentovic, and Nantes. In 843, they even spent the winter on the mainland for the first time. Paris suffered a sack on Easter Sunday in 845, and the Franks were compelled to pay a substantial ransom to convince the Vikings to depart. A Frankish monk, writing in the 860s, provided this harrowing account:
"The number of ships grows: the endless stream of Vikings never ceases to increase. Everywhere, Christians are victims of massacres, burnings, and plunderings. The Vikings conquer everything in their path, and no one can resist them. They seize Bordeaux, Périgeux, Limoges, Angoulême, and Toulouse. Angers, Tours, and Orléans are razed, and an innumerable fleet sails up the Seine. The evil spreads throughout the region. Rouen is ravaged, plundered, and set ablaze. Paris, Beauvais, and Meaux are captured. Melun's formidable fortress is reduced to rubble. Chartres is occupied, Evreux and Bayeux are looted, and every town is besieged."
As Viking raids grew more frequent, local kingdoms began granting lands at the mouths of rivers to Norse chieftains in exchange for protection and conversion to Christianity. The Frankish region of Normandy, for instance, was bestowed upon Viking chieftain Rollo in return for his defense of the Franks. A similar arrangement was made with the Danes Harald and Rorik for the island of Walcheren in Frisia, leading to their assimilation into Frankish culture.
In 859, a Viking fleet led by Björn "Ironside" (Jarnsiða) and Hastein embarked on a Mediterranean expedition, during which they raided Spain, Italy, the Rhône Valley, and North Africa for three years. Their fortunes fluctuated greatly during this period. By 862, after numerous raids and battles, only a third of the ships and crew that had set out in 859 returned, but those who did return were exceedingly wealthy. In the mid-tenth century, the Vikings made a return to Spain for raiding, although this time with mixed success.
