Ythanside certainly makes more sense than Tyneside for a song that is usually reckoned to be Scottish. Mains O'Gicht would also appear to place it in NE Scotland, rather than NE England. Both Gicht and Ythanside can be found in another song from that area - versions of Pretty Peggy-o contain lines such as:
The drums they did beat, on the bonnie braes of Gicht ...
and
Green grow the birks on bonnie Ythanside ...