She's an ancient land by time of Kull, sophisticated and wealthy but also decadent and stifling in its antiquity. With thousands of kings (apparently no ruling queens) in her past, the country is pushing 20,000 years of history (I set it around 22K). Its origins have been lost to history, although we do know its ancestors came from the east and warred with the serpent-men who rule the Seven Empires area after they had previously thrown off the yoke of the Giant-Kings.
By the time of Kull, Valusia is starting to fade, although in that way nations have of fading without really realizing it, with everyone in denial - eating, drinking, and being merry, and not noticing the barbarians at the gate (although in certain circles they do make snide comments about the one on the throne). Besides the barbarians at the gate (a small colony of Atlanteans on the coast), there is also a colony of Picts in Valusia on the border with Farsun, the Picts now having been allies of Valusia for a thousand years. Prior to that the Picts were also raiders on the coast.
The analogue I like to use to get a feel for Valusia is India, with ages sitting upon ages, grandiose architecture, and a history that goes back into legend.
Culturally we know the Valusians make use of slaves and have gladiatorial contests, eventually the gladiators can earn their freedom. They use dungeons for prisons (as opposed to labour camps, I suppose), and face bandits in the hills and mountains. The capitol is also called Valusia, a.k.a. the City of Wonders, a.k.a. the Crystal City of Valusia. Valusia itself is also known as the Land of Enchantment.
The Valusians seem to worship the mainstream world gods, but do allow the worship of Set (one of the Old Ones) to occur, at the Temple of the Serpent in the cities, but these are carefully monitored (at least under Kull) to make sure there isn't any crossover with the Great Serpent (the Serpent That Speaks, god of the serpent-men). It appears the Valusians have lost all real-world connection to the Giant-Kings, so they wouldn't be aware Set's temples could be a vector for intrigue coming from Acheron. Similarly, in a remote Valusian mountain city lies the Temple of Everlasting Darkness, dedicated to the God of the Black Shadow (another Old One), formerly governed by Guron. There's also a temple to the Great Scorpion there (you'll just have to read the stories for more on that).
Administratively (as lousy as that word is to describe the fantastic kingdom of Valusia), Valusia is broken into baronies, which can be used interchangeably with the term provinces. Technically though there are only two provinces, the large jurisdictions around the cities of Kamula and Valusia. Other cities have smaller jurisdictions around them that they oversee, mainly in terms of food production, which gives a bit of independence to all cities relative to the baronies they're found in. The Pictish colony is also a self-governed jurisdiction, appointing its own ruler.
The baronies are hereditary, passing from father to son (again, no female nobles seem to rule). Cities are ruled by a count, officially appointed by the king, but by tradition these are hereditary positions too.
Here's my list of the baronies, their capitols, and any notes on them. Those in italics are canon or pseudo-canon (for some reason in some editions of the stories names were changed from the originals - I've used the originals, but kept a couple of cool ones). The rest are made up by me for gaming purposes. The format for the list is "Barony - Capitol (notes)".
- Blaal - Blaal (also contains the city of Karaban and the Forbidden Swamp)
- Northern Shore - Mikkar
- North Marches - Northam (also has the Skull of Silence)
- Varana - Varana (also has the village of Hawks)
- Nabar - Zarawar
- Legan - Rowanbor
- Urungal - Urungal
- Strathspey - Strathspey
- Kachvar - Btoleny
- Alnakata - Kolderkon (also has the Tomb of King Kalenius, and Kolderkon is based on the RPG city of Ptolus)
- Yonla - Yonla
- Juven - Juven (also the Lake of Visions)
- Sylvilia - Wood
- Baradusa - Baradusa
- Yultana - Fanara
- Kartu - Komahar (also the Temple of Everlasting Darkness)
- Pictish Colony - Gat-nir
- Province of Kamula - Kamula
- Province of Valusia - City of Wonders (also the Forbidden Lake)