At the center of this blighted land, hard by the Worldwound itself, is the soot-choked city of Iz. Nearest to the mines of Sarkoris’s central plateau, Iz was always a center of metalworking and stonecrafting, but the whips of its demonic masters elevate those trades far beyond their volume and importance in the days of the barbarian kingdom. Life in the mines and foundries is exceptionally dangerous, as the convulsions of the expanding Worldwound periodically wrack the area with earthquakes and violent wildstorms that reshape wind, weather, and terrain in an eyeblink. Once a full day’s ride from the Worldwound, it is likely that within a decade or two, Iz will be entirely swallowed up by the burgeoning tumor on reality. Still, these raw emanations of chaos make Iz very popular with demons, especially those newly arrived on Golarion, and it is here that the Storm King recently rose to prominence.
Sources: Pathfinder Chronicles Campaign Setting