I believe Tom previously said, though this was months years ago so I could be wrong that it was previously intentional for characters to not know which regions belong to Zuma without traveling.
That was prior to the new map.
Obviously most the land is Zuma but if there was a spare rogue region than if the Zuma aren't controlling they probably won't care if you took it.
You should ask Barca about that. Remember us running around, collecting unique weapons?
