The World of the Dead and the Dying.
Mezarlik is a dying realm, with all the denizens of its blasted plains either dead, undead, or slowly wasting away. There is little of value on this desolate world, save maybe a hiding place from something Outside. The residents of Mezarlik however only dream of a way to leave their world before it kills them.
The Gods Have Left
There are no proper deities in Mezarlik, the greater outside gods having abandoned it and the lesser resident gods all been killed or fled somewhere else in the Void. Even the core deity of Mezarlik, Erishkiegal, is some sort of divine undead monstrosity, lurking beneath the surface of the plane.
The natives are not picky at all, worshipping anything they think might give them another few days of life, from obscure gods to natural or elemental spirits.
Magic works on Mezarlik as it does on most other realms, but it is always weaker and more muted than it should be, requiring greater effort for less results.
Necromancy is a fairly popular form of magic, raising the recently deceased to continue trudging along a bit longer.
Humans - Once a prominent and civilized culture, now reduced to tiny groups of scavengers and nomads, trying to stave off death for another day.
Cyclopes - One-eyed giants, nearly extinct.
Orcs - Their warrior pride shattered by loss and desolation, they scavenge alongside humans.
Lamias - snake-bodied people, mysterious myths.
Sphinxes - The body of a lion, the wings of an eagle and the head of neither, once powerful beings slowly turning to stone.
Girtablilu - "Scorpion People," the driders of Mezarlik. Created long ago by the desert-elves, who are said to be extinct on the realm. The Girtablilu, however, persist.
Undead - One of the most prominent "races" on Mezarlik, although even they are not immune to the rot affecting the realm, and on Mezarlik undead are not immortal but decaying.
Serpentborn - Spawn of Outsider Naga and native humans or lamias, Serpentborn frequently overbreed their societies to starvation.
All gone to dust now...
There are no great nations on Mezarlik, though there is evidence that there once were. Most remaining excuses for nations are small clans and tribes, banding together to try and carve out a bit of civilization and a better chance to survive.
Gocebe Clan - A tribe of nomadic humans.
Vahsi Clan - Another tribe of surviving humans, vicious and cruel cannibals.
The Rotwrap Dynasty - an undead nation led by a series of mummified rulers of previous nations, one rising to take over for the last one. They draw many other undead to them.
Dried-up seas and oceans