From the back of the book:
Once a lawless frontier less than a century ago, Roesone is one of the youngest states in all of Anuire. as the ruler of the land, you'll find that Roesone is surrounded by uncertain allies and dangerous enemies. Plots and intrigues creep through the halls of your court and shadowed powers are moving against you. It will take strength, courage and determination to keep your crown on your head - and your head on your shoulders.
This BIRTHRIGHT domain sourcebook is designed for players who want to take the role of Baron Roesone, the warrior regent of the land. It may also be used by players playing nobles, servants of the Baron, or adventurers from Roesone.