...I think it's also worth noting that once Westgard can take Ygg d'Razhuul, that will cut off the rogue regions between there and Arnor from the main body of rogue regions in the west.
That will make all monsters in those regions "dumb," and spawns there weaker.
Thus, Westgard can literally act as a shield for the realms of the east, and wiping them out will do you all a disservice.