It is the eastern-most region of the territory and borders the region of Cholla Springs to the west. The south, east and most of the north border of the region are defined by the San Luis River. The terrain in this area resembles the western parts of Kansas, Oklahoma, and the flat part of Texas called the Panhandle plains.
According to the Armadillo bank teller, Baxter Deaton, there is a lion in Hennigan's Stead that is being held by the locals. Although this is probably false, he could be referring to other NPC rumors that outlaws in Mescaloro caught Khan the Jaguar.
Hennigan's Stead is possibly one of the most biologicly diverse locations in the game because in the south having scrubland similar to Rio Bravo, swamps to the east, pine trees to the north, and oak savannah in the center.
In the far northern area there is a small area in the hills that juts out above the railroad tunnel that is snowy, much like northern Tall Trees. This is a treasure location in Undead Nightmare.