The plane of chaos has no native races aside from the five Lords. Instead, races from other planes are coerced or deceived into establishing residence to aid one of the lords in his quest for power against his peers. The denizens include: Genie (Vacuum); Azer (Ash); Salt Mephit (Salt); Dust Mephit (Dust). The Lords of Chaos form living shadows from the raw energy of chaos. They (and their avatars / orders) focus chaotic energy through the darkness of the material plane to embue negative energy into appropriate recepticles (golems, bodies, etc).
The Plane of Chaos is shrouded in perpetual twilight. No specific source of light exists, and yet long shadows are thrown across the uneven, rocky landscape. Bushes and creeping ivy struggle against slender, forlorn trees and tall dry grasses in the spaces between giant fingers of rock that protrude from the dry earth. Lightning silently breaks the dark sky at irregular intervals. The features of the landscape change as one travels across it, though all travel throughout the plane invariably leads back to the same destination: the palace.
Nestled in the shadows of a large, barren valley sits a giant palace ringed with five towers. At the center of these towers is a large courtyard with five ornate thrones. Seated in the thrones are the five Lords of Chaos, constantly struggling against one another to gain total domination of the realm.
The five Lords of Chaos represent our traditional Four Horsemen (Conqueror, War, Famine, Death), with the fifth being representing true Chaos. There is no specific hierarchy to the Lords, and none is more powerful than the others. Nonetheless, the one representing Chaos is perceived to be "better" than his peers, and they continually jockey for his position. The Lord representing Chaos sows discord amongst his peers to keep them pitted against one another as much as possible. The Lords are not immutable deities. Any of these five may be "killed" while in the Aether. The killer then gets imbued with the essence of the deceased and becomes the new face of that Lord. The new being retains all previous knowledge and memory, and takes on some of the personality of its killer. In this way, the Lords are fairly regularly changing, employing new tricks and tactics, and placing focus on different parts of the material world (and Planes). To date, the Lord representing true Chaos has not been killed in this way, though each of the other four have (several times). There exist a few cursed scrolls on the material plane that describe the nature of these beings, and various people's attempts to ascend to their station. No one knows for sure if any of the Lords have ever successfully killed one of their peers, thus leaving a vacuum in the structure. The Lords of Chaos make no secret of their attempts at allegience with the powers of the border planes. The Conqueror seeks to leverage Vacuum; War uses Ash; Famine makes promises to Salt, and Death brokers deals with Dust. They each work with their border peers to enact various complimentary schemes on the material plane. They also continually intimate to their border peers that if they should ascend to the position of true Chaos that their peer can then be elevated to their now-vacant station. To date, this has not occurred.
The elemental plane of chaos permeates the physical world through a variety of insubstantial and fleeting phenomena: a cold wind on a summer day, far away thunderclaps, a vague feeling of unease or mistrust in the company of friends, or fleeting nauseua are all examples of manifestations of Chaos. Chaos connects, and trickles out, to the material plane in dark places. There is no single point of connection; rather the plane of Chaos randomly connects to shadows on the material plane. Although no pattern exists from which to plot the next point of intersection, denizens of the material plane can chance upon these connection points from time to time. The Five are equally revered on the material plane through the symbol of the Pentagram. Individual worshippers of Chaos rarely align themselves with one of the Five, though exceptions have been known. For a mortal to know the identity of one of the Five is a true rarity, and usually only happens when one of the Five is exercising a plot against the others. The few mortals who ascend to the plane invariably have some direct connection. Worshipers of Chaos are present in all walks of life. The very naive and the very stupid are usually proud to display their allegiance to Chaos. As a result, they rarely rise above the level of petty thugs in small towns. The cunning and patient are often installed into positions of moderate power, just outside the limelight of public attention: a city magistrate, a trusted advisor to the local monarch, and similar "behind the scenes" figures are often attracted to Chaos, as they willfully seek to extend their own sphere of influence at the expense of those they ostensibly serve. The Five generally prefer to slowly corrupt the pure, rather than reward the egregiously greedy. Priests of other churches are particularly interesting to Chaos on a micro-level; while the machinations of national governments interest Chaos at a macro-level. War and siege are as interesting as barter and marriage in terms of tools to use to keep things unbalanced and unstable in the material world.
At least one scroll on the material plane is filled with the insane musings of an ancient ascetic contemplating what would happen should a power vacuum be created. This "eschatology of the planes" includes a number of powerful spells for channeling planar power in an attempt to snuff out all existence (material AND planar!).