If i understand correctly the big green round tribal region is forest or jungle surrounded mostly by mountains around the edges, right? And those rivers are flowing towards the center?
Then there's no (non magical) way for those rivers to just disappear. If elevation prevents them from flowing out to the ocean, then you would get a significant lake or multiple lakes at the lowest point, or at least a huge swamp. Forests require plenty of rain (unless they are on a river), and all that rain has to go somewhere.
The size of the dots on your latest dotted border are over-dominant. Your previous map had it a lot better.