Gotcha. I see the connection you made there.
On the "Eastern" thing. Unapproachable East, with the exception of Shou expatriots, is quite "Eastern Europe" in flavor (especially Rashemen), but not Oriental. That's what's banned. Wow, no ninjas in a Viking world. *Gasp!*
Dragon-themed casters are out because dragons didn't run rampant (well, as rampant as is typical of D&D) in Norse mythology. There are four dragons in the Norse myths, and two of them are of deity-level power (prophesied to kill deities at Ragnarok, or they are a cosmic force, whose rising heralds the coming of Ragnarok). Taking a bit of advice from GURPS Vikings, any dragons that show up should be rare and with important purpose/backstory. They haven't been running around the bar scene getting their jollies with human women, just so a PC can unlock his latent inherited dragon powers many generations down the line.
Scrolls: Just because there aren't magic item shops or intermediate sellers doesn't mean a wizard can't get scrolls. Sure, they might not be as plentifully available as some settings, but there are ways of getting your hands on such things. The Althing each summer is a large festival, serving as both a bazaar and a multi-day supreme court of law. People come from all over to trade their wares; mages make it a priority to come to such festivals, and swap spells with other mages. Character actions could also put you in good graces with another mage, leading to another avenue of gaining access to spells, et cetera, et cetera. Just because scroll access isn't on the level of instant gratification doesn't mean I'm going to screw over the players.
