[quote=TheSovereignGrave]
Generally there isn't. After all, the closer two nations are the easier it is to interact. Though you may want to discuss some mutual history, and just make sure there's no major glaring issues there.
[/quote]

Pretty much this.

You can have two nations nearby. But in my opinion it's basically a sin for there to be no consistency. In my opinion, a Japanese-like nation spawning from the same region as an Arab, Mesoamerican, or European state is very off.