Thought I'd quote this from a previous discussion.
Don't you see? The book is set 40 years after Oblivion. And Tamriel is threatened by a new evil. It doesn't seem like there's been any civil war, does it...
We can't say for sure. The plot synopsis and the amazon plot description speak of princes and suggest a new stable lineage, but the lore is chock full of little wannabe-empires popping up within the power vacuum that occurs after a central government has been offed. Cuhlecain, Emperor Zero, the one for whom Talos was a general, was one of those. He claimed the title of Emperor, had his little slice of territory, and attempted to grab more. 'Twas only thanks to Septim that he got anywhere with it (before he was assassinated and Tiber's throat was slit open).
This "prince" and his lineage may be of the same mold:
Little barony (heck, even a significant portion of a former province) claims right to the throne, amidst huge and colossal power conflicts against old alliances and fracture lines (Aldmeri Dominion, Cyro-Nordic alliance, Ra'Gada awesomeness, etc), and with multiple others claiming the right to that exact same throne alongside. Amidst squabbling, Giant Evil City of Doom™ comes into play, potentially either temporarily unifying the divisions, or widening them as all sides attempt to gain favor with said City of Doom or use the effects and fear to their advantage.
A prince does not mean an absence of post-Septim fallout and warfare. After all, it's was until recently a somewhat truthful joke in High Rock to, "Find a new hill, [and] become a king."
i'm guessing alot can happen in 40 years, considering how in one year the blackwood company left cyrodiil, the mages guild got a new arch-mage, the curse of the gray fox was removed, MD invaded tamriel, a gate to the SI opened, Uriel and all his sons died, the fighters guild got a new master, and countless other small things, now multiply that by 40 to get an idea of how much they are going to have to fill thats gonna' be one piece of work