BW/BW2 5th Gen = A completely new part of the pokemon world

[Dokukurage]

Hoenn isn't far away; neither is Sinnoh. The Regions are based on real parts of the world. So far, they're all in Japan. (Image from Bulbapedia, I take no credit or anything):

I think I've seen before that Orre is on the northern coast, above Johto or Kanto. I can't be sure; I never played either of the games that were there so I don't know the map very well.
Isshu is far enough away to restart the route system. This either means it's truly far away (speculation on it being New York City), or some story we have yet to hear eliminated the previous regions from having route one. (The possible nature/technology takeover? I find this one less likely.)

 

[batpee1]

Isshu is far enough away to restart the route system. This either means it's truly far away (speculation on it being New York City)

lol unless it was called manhaten or bronx there is a really small chance of it being in new york city.

 

[Majora_787]

It could still be in Asia. I talked to my friend about it, he thinks Isshu could be in China. That would explain a few things.