Baal Hishutash in the far north of the Kindattu Mountains, and nearby Tahrah at the mouth of the Mundu River, have apparently lost contact with the rest of the Baal Hamazi cultural area. Refugees have been streaming southward, and they refer, in vague and garbled rumor, to the return of the first Priest-King; someone claiming to be Hutran Kutir, the semi-mythical founder of the Baal Hamazi Empire. He's not happy that his empire has fallen apart to squabbling city-states and hordes of nomadic tribal barbarians, and he's dead-set on reestablishing his empire again by force of the sword--and he's not interested in anyone's stories of competing claims to the throne, appeals to freedom and equality, or excuses that this is nothing more than a somewhat prolonged interregnal break. This empire is his, and he wants it back. Now.
Of course, those rumors are garbled. What exactly is going on up north in the last few months, and why? Although my idea for this predates the rise of ISIS by some years, I see this as a similar phenomena; an idealogue appealing to romantic and nationalistic notions to swiftly conquer and establish a new state in the area, and a threat to the somewhat steady and stable city-states that already exist, as well as any border regions, since this new state is fiercely and violently expansionist. But, so far it's only taken on an area of rather uninhabitable wilderness; the Hamazi Canyonlands, a large area that today resembles parts of the Colorado plateau, specifically the Canyonlands National Park and Grand Staircase-Escalante National Monument, and the northern Kindattu Mountains, a range of alpine peaks that runs north-south just to the east of the Canyonlands, and the very north of the Indash Salt Sea; a large endorheic sea that would be equivalent to Lake Bonneville. Because this area is so desolate and inhospitable, in general, this newly established and conquered state has to expand. The lands of Baal Hishutash can not support a much higher population than already exists there, and Tahrah exists mostly on fishing and trade; it is surrounded by salt flats that are completely non-arable.
Rather than answer directly what the story is with this Hex-King, as he's called, let me explore some possibilities, and then we'll see which of them I like better at some future date when I need to define it. I see basically three main ideas, although all of them have subtle shades of nuance that can also be applied.
1) Hutran Kutir really did return. It was prophesied, according to some (although nobody can find where this prophecy was documented, and it may be propaganda generated after the fact) that he would return in the Empire's darkest hour to save it--a. la King Arthur. The current state of the Empire certainly supports this interpretation, as the Empire has essentially ceased to be entirely, and it would take a new conquering of the now independent city-states to reestablish it. The mechanism of this return would be unknown, but Hutran Kutir had powerful sorcerous allies, the equivalent of a member of the Heresiarchy, and he may have been able to access magic that enabled him to live indefinitely. Of course, if that's the case, then where has he been the last several centuries since his reign?
2) Hutrain Kutir has been brought back from the dead. This is significantly different in scope from the option above; it posits that essentially Hutran Kutir is some kind of revenant, ghost, or other type of undead returned from his tomb in the sand-buried ancient capital of Baal Hamazi. This isn't necessarily a stretch either; at least one of his rumored advisers during his life was a vampire from Tarush Noptii.
Not that Hutran Kutir even in his normal living state wouldn't be a nightmare tyranny run amok, but this is, of course, significantly worse; an empire of the Undead ruled by an undead Hex-King wouldn't just be a nightmare for the oppressed, it would be a nightmare to any who live.
As an aside, either of the first two means a new, major sorcerer appeared on the scene essentially out of the blue. This will no doubt significantly impact the delicate balance of power and tense, Cold War-style peace that exists today between the members of the Heresiarchy.
3) A more prosaic option, of course, is that "Hutran Kutir" is an impostor; someone else who merely is using his legacy and his legend to claim power. This doesn't mean that this impostor is some chump; in fact, if this is the case, most likely it's one of the Heresiarchy posing for the time being as Kutir in an attempt to quickly amass an army of fanatical soldiers and a mortal kingdom of some means. This will also, needless to say, spark the rest of the Heresiarchy into action once it becomes known what's going on.