The reason why I'm so insistent on the "Irish" sound in Irish music, whether from Donegal, or other counties, is that I hear melodic patterns in Irish jigs and reels that mark them with the quality that makes them Irish. The Celtic music world is indeed mixed with various musical influences, but one can hear the "core" of what makes music from one country different than another. Being a fiddler, I can also experience the feel of these differences in how the tunes are bowed and, and of the left hand embellishments that give these tunes their national flavor. As for the Shetland Islands a good point, that Shetland is not a nation. It still, though, has the qualities that differentiate it from its neighbors, though heavily influenced by its neighbors. It is like it is musically a nation, with its own distinctive sound.