The Vikings and Normans are ethnically linked because of their common descent from the Norwegian group of Viking raiders and settlers of the ninth to eleventh centuries. The Vikings per se came directly to Ireland and Scotland during this period, and in Ireland they established the first towns as coastal trading centers, as merchant activity was a natural second stage to their original ferocious naval raiding. They became completely Gaelicized. The twelfth century brought Anglo-Norman settlers to Scotland, and Anglo-Norman invaders to Ireland. The Normans first appear as mixed Danish and Norwegian settlers in tenth-century Normandy, a province of France which these Vikings wrested from the French and made a dukedom, and from which province they subsequently invaded England in 1066. Their original introduction into the Frankish and Gallo-Roman world in Normandy changed military technology forever, for these acculturated Vikings, afterwards known as Normans, swept forward from Normandy into England and later Gaeldom with "Mote and Bailey" castles (where the Gaels had raided, exacted tribute and then gone back to their own territory, the Normans confounded the Irish by actually squatting on the invaded land with castles, thus physically denying it to its erstwhile owners). The Normans also utilized disciplined and armored Frankish-style cavalry, thus introducing the mounted knight. They invaded both England and Ireland with similar success, though in the Gaelic area they were influenced as much as they influenced. They eventually became to a very large degree, "more Irish than the Irish," adopting Gaelic lifestyles, language and kinship patterns.

The Viking Clans