The tongue is not only a vulnerable organ with many blood vessels, it is also a tender cut of meat, very tasty if you ever tried cow, pig (or reindeer!) tongue.
If I remember correctly, the landnámabók mentions Gaelic monks living as hermits on islands off the coast of Iceland. Whether they had lived on the mainland before and were chased away to the fringes when the vikings arrived is unknown. Whichever way, the vikings treated Iceland as virgin territory that they did not have to fight over (if they had, they would surely have boasted of it!
Stories about the Shetlands do mention, for instance how arriving Vikings drove the remnants of the gaelic or pictic natives to extinction (or "underground" as the vikings believed; they became latter day pixies and trows).