Oerth

Oerth is the original setting of the world of Greyhawk, Gary Gygax's original campaign setting, in some ways predating RPGs themselves. The original background reflected Gygax's vision for his campaign, very much based on high medieval Europe.

Since then TSR have done a lot of messing around (in my mind) to Greyhawk, with a world-spanning war and lots of changes. I rather preferred the pre-Greyhawk Wars version of the background, so feel that I am relatively free to completely retcon a bunch of stuff into it, with my own timelines, and a lot less anthropocentric, and a bit more variety between nations.