Not much is known about this part of the Wasteland. Some Northern Wasteland settlements — Wellspring, and the Hagar Settlement — have reached trading agreements with the town of Gunbarrel, the capital of the Southern Territories. Dan Hagar leaves to Gunbarrel by the time Nicholas Raine secures the future of the Hagar Settlement and leaves to the town of Wellspring. Mayor Clayton regularly mentions the trading agreement over the speaker system in the town, and Sheriff Black helps to arrange shipments that go to the Southern Territories and protect the caravans when they leave Wellspring.
Though the player can't access neither the Southern Territories nor the town of Gunbarrel, the locations may have been a part of a planned DLC for RAGE.