With regards to the idea of the chief deity in a number of mythologies being from the north (which I can't corroborate), in one sense Melkor was the chief deity of Middle-earth, since he worked so much of his evil in the land itself. All too often the good Valar seem to be doing nothing but sitting on their kiesters in the West; the only Vala who seems to do the same sort of "power running through the land" is Ulmo calling through his waters (and incidentally, he's the one who got most involved in the Exiles' and Men's affairs).
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