The main question - how do you go from the dying Elysian Empire of EY516 (EY = Elysian Year) to the large city-states of EY1666 Camalynn?
Camalynn, inspired by England and with some inspiration from Russia and the Scandinavian countries as well, at least culturally and in terms of naming conventions, was united in EY534 by the former Elysian soldier, turned popular general Aeron Dragonshield, who became King Aeron I.
Aeron I and his immediate descendants fought against the Wolf Horde - the Chaotic berserker armies of Outer Kvenland and their lycanthrope and beastman allies.
Aeron III struck the killing blow against Chaotic Kvenland in EY 591, slaying the dread Werewolf King, Rolf Redtooth and routing the Wolf Horde. This led to an uprising of the Kvenlander population, which was Neutral for the most part, against their Chaotic overlords.
Camalynn was always a bastion of the austere, zealous Grey Church, as the power behind Aeron Dragonshield's rise to power was the Grey Church's Matriarch Vindicta (nothing makes a 9th level fighter's life easier than alliance with a politically savvy, highly popular 13th level priestess). The older Bright Church was, and is, always present but always as a secondary power.
Fast forward several centuries, and Camalynn began developing as an imperial power of its own, eclipsing its neighbors Leoneis and Rayanes. Around EY1200, it even began conquering offshore lands to the far west, and at its height, it reigned over Leoneis as well.
But all fell apart in the Bastard War.
King Alfred II of Camalynn died in EY1388 without legitimate issue. He had, however, two illegitimate sons - Gunnar the Bastard, born from his unlawful relationship with a kitchen maid, and Albert the Hunchback, born from incest between the King and his sister.
Albert the Hunchback was the eldest, and with better pedigree (born from the union of a King and a Princess, no less), but incest is considered an abomination by the Grey Church, so Matriarch Gloria III refused to anoint him and instead blessed his half-brother, Gunnar the Bastard.
Albert, with his eyes set on the throne, traveled all the way to far Elysia to be blessed by the Bright Church's Pontifex.
Each claimant to the throne had several prominent noble houses behind him, as well as the blessing of a Church.
Thus began the fratricidal Bastard War. It combined religious strife with personal and family ambitions, a deadly combination for the kingdom and many of its residents.
This also spilled over into a religious conflict in neighboring kingdoms.
Both Gunnar the Bastard and Albert the Hunchback fell in the Battle of Darkford in EY1399. Legend has it that they struck each other in an epic duel, but in reality, Gunnar the Bastard was killed by a cannonball - a recent innovation - while Albert was slain by an errant arrow. Both died without issue.
The remaining noble houses tried to claim the empty throne but none had a strong legitimate claim to it. Thus, they continued the war for half a century. This war engulfed Camalynn, Kvenland, Leoneis, and Rayanes and had, in addition to the machinations of nobles hungry for thrones, a strong sectarian religious element.
The war ended with the exhaustion of all belligerents, and wide devastation of the lands, with the Peace of Mont Rayenn in EY1444, signed by the remaining noble houses and both Churches.
Each House retained its holdings, but none gained the throne. All parties agreed not to crown a king over Camalynn except by agreement of a majority of the noble houses. The other kingdoms, where there were legitimate heirs to the thrones, were restored. Both churches recognized each other's legitimacy and were allowed to operate without restriction across Camalynn and its neighbors.
Recovery, fueled by recent technological advances, focused on Camalynn's major cities, each a seat of a Great House.
Thus, contemporary (EY1666) Camalynn is a land of city-states, most ruled by Princes, and one by a Senate after overthrowing its Prince.
And the Throne sits empty. None has a strong enough legitimate claim to it to convince the noble houses to enthrone him.
But "someone" (read: power-hungry PCs) could, "theoretically", force the noble houses to elect him/her as a Monarch by force of arms!