All locations referenced are on the western portion of this map.
There are six elements and their respective planes - fire, earth, air, water, life and void.
Beholders are of the Void and Dragons are of the four material elements. The fey are of Life.
There is no pantheon of gods, only the "old faith" embodied in the worship of life and nature.
Elementalism, or dragon magic, calls upon the four material elements. One cannot practice void and draconic magic at the same time.
The campaign history begins with the domination of the "good" races (humans, elves, dwarves and halflings) by beholders. The eye tyrants forced them to see to their needs and to act as their playthings. The ultimate goal of the beholder empire was to eventually replace all life with Void. A whole new race was created, the eye-kin, as part of this attempt. Massive cities twisted in odd shapes to fit the variety of aberrant beholder forms were built along with towers and laboratories.
Only two places, the elven Isle of Alucinor and the dwarven Iron Ring, stood fast against the beholder's rule. When a massive war began in the east against an enemy powerful enough to level entire cities, these two bases acted a staging points in the revolt of the western lands. A new race of people claiming to have been sent to aid the revolt, the Dragonborn, were also useful in teaching the ways of the material elements and established a school on Alucinor. Between the onslaught in the east and the revolt in the west the beholders were forced to yield and flee to wherever they could hide.
Using the bried outline above we can suss out the following rule elements (3.5 edition D&D).
Humans, elves, dwarves and halflings each play their normal roles though the elves of Alucinor are very religious and the dwarves of the Iron Ring are survivalist bastards.
Dragonborn are welcomed in many places as saviors but some people are suspicious.
Eye-kin also rose up against the beholders and for that they aren't killed on sight. They have varying degrees of acceptance throughout the land.
Aberrations are everywhere, not only beholder-kin but their many horrid experiments breeding in the wild.
The Fey were annihilated when the beholders took over and the few survivors are now treated like lesser gods.
There are no real races of humanoids aside from the player races.
There are no angels or demons, only elementals.
Corporeal undead exist, but they are corpses filled with Void and positive/negative energy doesn't play a part.
Dragons... are mentioned later.
There isn't really divine or arcane magic per say so this is a chance to break out all the non-standard 3e classes:
Fighters and rogues exist because why wouldn't they?
Druids are the new clerics which means healing isn't as easy as before.
Neutral paladins (Avengers?), Rangers, Scouts and barbarians of course.
The Warlock and Hexblade can exist as willful channelers of Void magic. (I've got a invocation using Hexblade variant sitting around somewhere...)
The Dragon Shaman and Dragonfire Adept for some draconic goodness.
The Elementalist from Occult Lore for what the dragonborn teach.
The Minstrel (a magic song only bard I've got somewhere) and Skald (a warrior only bard).
These are the basic, brainstormed elements of the setting - the building blocks. The actual setting itself will continue in Part 2...