There are various competing theories that have addressed the early colonisation process, although it is clear that the Northern Isles were the first to be conquered by Vikings and the last to be relinquished by the Norwegian crown.
Der findes forskellige teorier om, hvordan koloniseringsprocessen er foregået, selvom der står klart, at Northern Isles var de første, som blev erobret af vikingerne, og de sidste som den norske krone gav afkald på.