 The traditional explanation is the earldom hypothesis.This assumes a period of Norse expansion into the Northern Isles and the creation of an aristocratic dynasty that lasted well into the Medieval period, which exerted considerable influence in western Scotland and Mann into the 11th century.This version of events is essentially as told by the Norse sagas and is supported by some archaeological evidence although it has been criticised for exaggerating Orcadian influence in the "Suðreyar".