[mlangsdorf]

I ran my first 30+ sessions of Dungeon Fantasy without a map, more than a sentence or two of background material, or anything else like that. People delved and had fun.

So yes, while you could use a map of North American circa 1380 AD as a basis for a setting, I don't think you need to through that much effort.

Your background can be as simple "There is a Town on the edge of a wilderness." That's all you need before you write a dungeon and come up with some rumors and start playing.