From the back cover:
Honor Thy Father
The Book of Sires radically expands the Family History system first presented in the King Arthur Pendragon core rulebook to encompass knights from any of the nine realms: from Aquitaine to Cornwall to Cumbria, and many points in between!
Use this book to generate a rich year-by-year history of your character's parent and grandparent (beginning as early as the year 439), with additional material to cover campaigns starting as late as the year 509.
Witness the sweep of history from the perspective of your character's ancestors, as they fight in legendary battles, see mighty kings rise and fall, and build their own modest legacy—of which you are the latest scion!
Will you bring honor to your family name, or shall the line wither and die with you?