Norse. The main Norse text is the Orkneyinga Saga, which was written in the early 13th century by an unknown Icelander. The English and Irish sources are more contemporary, but may have "led to a southern bias in the story", especially as much of the Hebridean archipelago became Norse-speaking during this period. Dates should therefore be regarded as approximate throughout. The archaeological record for this period is relatively scant, although improving. Toponymy provides significant information about the Scandinavian presence and examples of Norse runes provide further useful evidence. There is a significant corpus of material from the Gaelic oral tradition that relates to this period, but its value is questionable. Language and personal names provide some difficulties. The former is an important indicator of culture but there is very little direct evidence for its use in specific circumstances during the period under consideration. Pictish, Middle Irish and Old Norse would certainly have been spoken and Woolf (2007) suggests that a significant degree of linguistic balkanisation took place. As a result, single individuals often appear in sources under a variety of different names. Colonisation process Given what is known about the frequency of sea transport around the Hebrides and Orkney in the 7th century it is highly likely that Gaelic and Pictish sailors were aware of Scandinavia before the commencement of the Viking Age. It has also been suggested that an assault by forces from Fortriu in 681 in which Orkney was "annihilated" may have led to a weakening of the local power base and helped the Norse come to prominence. Scholarly interpretations of the period "have led to widely divergent reconstructions of Viking Age Scotland" especially in the early period and Barrett (2008) has identified four competing theories, none of which he regards as proven. 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. The second of these theories is the genocide hypothesis, which asserts that the aboriginal populations of the Northern and Western Isles were eradicated and replaced wholesale with settlers of