The Norwegians and Danes, who in ancient times occupied the Orkneys and other islands on the coast of Scotland, divided these islands into two groups: to the former they gave the name of Nordureyar, or Northern Isles; and to the latter, which included the western islands, that of Surdureyar, or Southern Isles. By Sodor, therefore, is meant the western islands of Scotland, especially those most contiguous to the Isle of Man, which, with them, formed a diocese.