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.
Vikings
A consequence of the available written sources, which may have coloured how the Viking age is perceived as a historical period, is that much more is known of the Vikings' activities in western Europe than in the East. One reason is that the cultures of north-eastern Europe at the time were non-literate, and did not produce a legacy of literature. Another is that the vast majority of written sources on Scandinavia in the Viking Age come from Iceland, a nation originally settled by Norwegian colonists. As a result, there is much more material from the Viking Age about Norway than Sweden, which apart from many runic inscriptions, has almost no written sources from the early Middle Ages.