Aah here we are!
Thank you a lot! Even if I use 3.5 edition rules (as said main goal is to use most exotic materials like tome of magic and incarnum to build empires/world), those rules can be used in 3.5 edition just fine (or minor adjustments if need be).
Is it worth maybe thinking about the different levels these different kinds of power are operating at, or whether it's necessary to have them all in the same setting?
I only ask because Yon Typicalle D&D Settynge tends to insist on having a kitchen-sink throw-everything-at-the-wall-and-see-what-sticks approach to different grades of Power -- thereby putting them all on relatively equal footing -- whereas another type of setting can make use of one or two types of "empire" as the prime movers in the setting and have others subordinate or ancillary to them (which, FWIW, is probably more "realistic" for whatever value you're willing to assign that term?).
Well, idea is that most kingdoms/empires seek world domination with one reason or another. Where as fewer empires just fight to preserve what they already have.
So overall I meant there are major big shakers (let's call them titans) who fight each other or plot against each other to get upper hand. Idea is that there is constant rolling conflict and warfare between the titans.
Where as free nations/kingdoms is term describe nations who are smaller and can be subservient or independent (or if big chain of alliances; even oppose them) towards the titan empires. Now to clarify what each kingdom is about and why;
Dragon Empire = World domination in name of emperor/empress. The ruler desires rule whole world as it's god emperor/empress out of sense of personal greed and ego (god complex). We are speaking of elan red half-dragon who embraces his red dragon heritage and top of that haves ego and sense of superiority of himself as he/she has lived over +3,000 years and ruled most of that time as emperor.
Human Empire = World domination because it's human destiny to rule the world like Zarus (their deity) did as mortal as humans are superior race (think middle age crusader nazis).
Kingdom of Madness&Aliens = They seek corrupt and assimilate whole world in name of alien demigods who influence their half-daelkyr offspring through psionic whispers. All in name of becoming greater and more powerful organism as part of evolution perfection. To them they see world as imperfect, sick and crippled and they seek 'cure' it by infesting it with chaotic bio-organic mass.
Demonic Kingdom = Seek establish themselves top of the food chain and so being rulers of the world comes naturally to them thanks hefty demonic influence and sense of self-superiority. But most of all they view other kingdoms weak and they despise weakness and so they seek it as natural behavior to challenge other kingdoms and test their might; if weak they are subjugated. If strong; focus grow stronger to empower them later. Might makes right is name of their game.
Undead Empire = They were originally hunted outcastes from all other kingdoms who banded together form own kingdom and now seek establish power and strength to continue existing as they wish. Some undead may be driven to purge all life from the world but central governance cares little at all is world alive or dead (vampires care to extend to get fresh good quality blood to keep small number of living humanoid as lifestock/servants very least).
Kingdom of Souls = They mostly seek to preserve themselves and their way of life and independence. A council runs the country and council members are voted from general population (democracy without president). So they mostly defend themselves but Rilkan may be most aggressive towards exploring and expansion (and that causes conflict with two other races factions).
Elven Kingdom = Pretty much same deal as Kingdom of Souls; preserve themselves they need remain strong or else swallowed whole by other empire and none of them appear appealing.
Hordelands = The mercenary kingdom run by monstrous humanoids (gnolls, orcs, goblins, ogres, trolls etc) is mostly bloody tribal warfare filled land where mercenaries to other kingdoms come in name of coin (or bloody glory). But if tribals would combine they have military size of three titan empires and it's potent thanks constant conflict and wealth brought by mercenary activity. But thankfully tribals love very much hating each other and fight to their last breaths (and continue breed like rabbits). Some tribes work together or have cease fire treaties but these usually do not last long (and some work only during mercenary work while home they continue their fights).