Oh, regarding a new region -- it would probably be good to put it slightly further way in the forest if you can.
^This is the most recent map.
Ideally, I would like to keep Scribel Region itself a beginner region with low-level monsters. I would also like to avoid filling Scribel with literally everything (e.g. demon lords, dragons, uranium, more...

), and I would encourage players to try to shift content into other regions or new regions as much as possible. This way, the world isn't incredibly lopsided with tons of ridiculous things happening around a small frontier city and nowhere else.
If you want to eventually make a new forest region, I would recommend extending Scribel Forest further to the west or east -- and then putting it there so it does not conflict as much with the content that other players might have in the nearby forest (especially if you are making the dragon the "ruler" of the forest -- that nobody else has so far encountered).
Keep in mind that there is a recent rule addition -- one Rank A NPC character allowed per player. Since I'm assuming your dragon is very powerful, presumably that would count as your one Rank A+ NPC addition to the world of Tonia.