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 raid warfare and tactics
Vikings, according to Clare Downham in "Viking Kings of Britain in Ireland", are "people of Scandinavian culture who were active outside Scandinavia... Danes, Norwegians, Swedes, Hiberno-Scandinavians, Anglo-Scandinavians, or the inhabitants of any Scandinavian colony who affiliated themselves more strongly with the culture of the coloniser than with that of the indigenous population."