It makes sense to me now, as I'm sure many of you guys have thought of this as well, as to why there is so much territory on the Skyrim map (around the outer edges) that we could not go to. It seems that there were vast amounts of land along the borders that were inaccessible in the regular game that will probably be opened up in the up-coming DLCs. Just a though.

The land outside the borders are other provinces...

There is that gate in the Rift that leads to a new area That could be where the Dawnguard castle is.

I know some of it is. But I think there's quite a bit, especially south of the Throat of the World that we just can't get to.

Has Bethesda ever done a DLC where they went to another province? I know in Oblivion they didn't and in Morrowind (never played it much) I'm pretty sure Bloodmoon was just a separate island. I doubt they'd add Hammerfell or Morrrowind to the game in the form of DLC but I could be wrong.

You may find this video interesting.

http://www.youtube.com/watch?v=PlbA2qiXsf0