This Hell was spawned in some far away world where magic and the other laws of nature worked very differently, and history must have taken a very different course.
The hell can best be descried a chaotic demonic steam punk dystopia, filled with failed states, warring cities and wandering nomadic tribes, all utilizing great infernal engines of war to wreck havoc on their enemies.
The hell is heavily populated and expansionistic, often opening portals into neighboring realms and raiding them for treasure and slaves. Their mastery of Infernal Machines make these invasions very dangerous, fortunately for their victims, the hell seems extremely disorganized politically, so these invasions are mostly carried out by raiding gang not large organized states, so manifest more like never-ending raids.
One of the adjacent realms that this hell is invading is The Hell of Boiling Blood.