Great Kingdom Map, Gary Gygax, 1971, Territories of the Great Kingdom
Check out this early version of what would eventually become Gygax's World of G'hawk. Grodog sent me a link to it because, I suspect, he wanted the wingnut perspective on this thing. As you most likely recall, I ran a piece on the origins of the Oeridian people way back--seems like only yesterday, eh?
Anyway, my initial thought: See that valley in the mountains between Perunland and Neron March? Impact crater from the Oeridian mother ship, obviously.