Yeah, it probably would have been better to say that they are immortal but declining. Their souls when they die go to a kind of nether, an aetherial plane where they can either choose to reincarnate or not. However mortal mages had found a way to stop this from happening by magically sealing the Dragon soul, binding it to the mortal plane and preventing the dragon from reincarnating. Most dragons were sealed, some decided not to reincarnate since the race had declined and they would be hunted relentlessly, and the very few remaining are hiding amongst the mortals just trying to live peaceful lives. They generally live in exile since they don't whither and age like the rest of the mortals around them.

As for the map, I appreciate it but it's unnecessary, I have a map that my friend made for a D&D campaign of this. I just need to get it from him.