The emigration of Gaels to Cape Breton has also resulted in a unique strain of Gaelic music evolving there. The six Celtic nationalities are divided into two musical groups, Gaelic and Brythonic, which according to Alan Stivell differentiate "mostly by the extended range (sometimes more than two octaves) of Irish and Scottish melodies and the closed range of Breton and Welsh melodies (often reduced to a half-octave), and by the frequent use of the pure pentatonic scale in Gaelic music".