The Umbrella Corporation wrote:
I also believe the Baku and Sona are not trespassing. They were there before the Federation, Romulan, Klingon empires were formed.
The ring planet was the Romulan Empire's territory at the time that the Baku arrived there. This comes from ENT during the augment arc.
Um this is the reveant quote where they discuss the Briar Patch and I don't see anything about the Romulans being mentioned at all.
In fact it sounds like the Klingons weren't that interested in the area at all either.
The Augments wrote:
SOONG: Once we're safely through Klingon space, we'll set a course for these co-ordinates. The Klingons call it Klach D'kel Brakt. I call it the Briar Patch. It's a little catchier, don't you think?
LOKESH: Briar Patch?
SOONG: You should have read more of the books I left for you. The region is flooded with radiation from supernova remnants. The Klingons have never mapped it. There are signs of at least two habitable planets inside the Briar Patch. It's unlikely anyone will find us.