Caer Uffren is the primary city of the Western Isles. Technically it is the home of the Thalassocrat of the Western Isles, who is currently Etain Muirghein. However, the proper place for the thalassocrat is upon the quarterdeck of their morcurrach.
That does not mean Caer Uffren is unimportant. It is the center of Islander culture, religion, and learning. It is the home of the greatest shipwrights and maritime scholars in Shijuren. These are the ones who have developed the morcurrach, which give the Islanders their maritime superiority.