Thanks, Firefoot. I was trying hard to refrain from answering that one, but my strength of will was slowly beginning to falter.
Anyway, I've decided I'm allowed to go for another one now...
So, is this Dorthonion?
Edit: Actually, you may be looking for Ladros...? When Boromir was appointed Lord of Ladros, those who had moved north gathered there ... so, yeah, Dorthonion or Ladros.