As far as I can tell, the great thing about the Dragon expansion is that over time, dragon scales cover the whole region forcing players to move into the inner region or suffer the wrath of the dragons.
When adding expansions such as the Dungeon or the City, there are many more spaces in the same region.
How is this interpreted?
As far as I can tell, this can be interpreted one of three ways:
1) Each expansion only really covers one square, e.g. City = the city sqaure, Dungeon = the Ruins square etc. So when you draw you have to place your token on the normal outer region (not expansion).
2) The other region now includes the expansion pieces, e.g. City and Dungeon, and so it takes much longer to fill every space with a scale slowing down the dragon effect.
3) Each expansion board is a separate region.
Or it could be something different.
We currently use 1) so that the Dragon rules are not affected. If you're in the City or the Dungeon, when you draw a token, you look for empty spaces on the main board.