The map is confusing, as you need to access several places under the ice in the gameplay. Undella Town and Segeiha City are required in pre-Elite 4 gameplay. In my opinion, the region was frozen by Kyurem somehow, and then thawed out. While frozen, new towns were established so there could be more gyms. It may start out frozen like this, and then thaw out mid-game, so that you can access the eastern portion of the region. What if Kyurem goes on some sort of rampage or something, freezing this and you are required to catch/defeat him, calming him enough to unfreeze Unova? What if this was only frozen for seconds or minutes, instead of 2 years? That makes sense to me, if there were still air bubbles or something above towns and areas that need it.

But it seems Team plasma captured Kyurem, which made unova freeze

Yeah… that post was from a long time ago :p

and they have revealed that in black2 there is a water cave and in white 2 its a lava cave …and i belive that you may be correct and that may very well be where this new cave is

Hm, Sunnyshore? That would be Gin (She posted in this thread quite a bit too, just a little above your post). Can you link us to where it says that she said there are two pages to the town map? Was this not just speculation? (I’d like to hope there is a second page, as exploring is my favourite part about Pokémon games, however as far as I’m aware there is not anything that suggests this yet).