Recently, I read a book by Timothy P. Bridgman calledHyperboreans: Myth and History in Celtic-Hellenic Contexts. It's not a bad book, and Tim himself is a very nice individual (I've met him in person perhaps twice at various conferences over the years), though he repeatedly stresses how all of these matters are fictional, mythical, and not real, which as a polytheist kind of gets on my nerves on occasion, especially when it isn't necessary to repeat it (or even say it at all). What his basic premise is, though, is that in earlier strands of Greek belief, Hyperborea seems to have been to the north and east of Greece, possibly in the territories of the Scythians and/or the Thracians, because Mt. Haemus in Thrace was considered the spot where Boreas blew from, therefore Hyperborea would have been beyond that. However, as time went on and as contacts with the more western barbarian peoples like the Gauls/Celts increased, Hyperborea seemed to shift locations somewhat from the north and east to the north and west.