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.
History of Ireland
The Vikings were expert sailors, who travelled in longships, and by the early 840s, had begun to establish settlements along the Irish coasts and to spend the winter months there. The longships were technologically advanced, allowing them to travel faster through the narrow rivers. Vikings founded settlements in several places; most famously in Dublin. Most of the settlements were near the water, allowing the Vikings to trade using their longships. Written accounts from this time (early to mid 840s) show that the Vikings were moving further inland to attack (often using rivers) and then retreating to their coastal headquarters.