Kadesh is the eternal kingdom upon the Eternal River.
Over 10,000 years ago a nercomancer priest rose to rule the first human civilization. He promised the people heaven on earth if they would only follow him. He actually was able to deliver on this promise through the power of necromancy. In exchange for use of their body after death, they would have all of their needs taken care of.
The skeletons and zombies from the deceased make up the workforce and the basic troops of this realm. The living residents enjoy the highest standard of living in the world, living lives of complete decadence if they so choose. When they die, their mortal spirits move on, and their bodies join the rank of workers and soldiers. Long years of peace means that their is at least 20 dead servants for every living man.
This life of decadence is not without cost however. Choosing to live like this means giving up all power to the priesthood. The priests make all decisions of import, and will go to nearly any length claim a body of their people. Choosing to give service to the priesthood gives individuals power, and the promise of a higher form of undeath. The intelligent undead make up the hierarchy of the priesthood (though not all priest have cleric levels, they are still titled priests). Liches and mummies are generally the most important of the undead, though more aggressive undead such as vampires and ghouls have been created for foreign operations.
Most of the time Kadesh doesn’t involve itself in affairs outside of its realm, but it was forced to proactively defend itself by fighting in the 3rd phase of the Long War As a result it gained the territory that the Gnome homeland originally was. They held onto this territory for 45 years mostly out of inertia, and gave it back when the 7 kingdoms declared a crusade 5 years ago. The 7 kingdoms don’t trust Kadesh, since giving in doesn’t fit in with their feudal mindset. Kadesh doesn’t really care what the 7 Kingdoms thinks. Its plans generally don’t include outsiders, and undead have much longer views of things.
Kadesh’s Golarion equivalent is Osirion.