Like all of the "Player's Secrets..." books from the Birthright setting, this is a great resource. These books cover in fairly great detail the politics, geography, economy, etc. of a given nation. They also provide a 'who's who' in the nation. And while some of these provide information on the default ruler of the nation, these books are primarily designed with the understanding that a player is running the nation. Basically, "The nation is yours...now hold onto it."

In the case of Stjordvik, it is one of the more 'good-aligned' Rjurik nations (think Norse), which has a strong economy, trading beyond their regional borders. That said, it has enough enemies that you won't feel too secure.

While you can run this with any 2nd ed. D&D setting, it is best used in conjunction with the Birthright Campaign Setting, as well as the regional source box: The Rjurik Highlands.