North Germanic peoples
Vikings were also active in Francia. Some of these Vikings would sail through the Strait of Gibraltar and pillage the coasts of the Mediterranean Sea. In the early 10th century, a group of Vikings under the leadership of Rollo settled in Rouen, France, and established the Duchy of Normandy. The descendants of these Vikings, known as the "Normans", would in the 11th century conquer England, Southern Italy, and North Africa, and play a leading role in launching the Crusades. Sub-groups of the Normans include Anglo-Normans, Scoto-Normans, Cambro-Normans, Hiberno-Normans and Italo-Normans.
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.