It says in his history that he was the leader of a battle convoy in a "certain kingdom". What was that kingdom called, after giving it much thought I came to an idea that Brooks history could be some what related to Sir Daniel Fortesque in the way of what the kingdom could be, Gallowmere. I have always thought of Dan and Brook meeting, there both sword wielders, both dead and alive, though Dan has one eye and no lower jaw, Brook has no eyes and hair.
So just saying, Brooks history could make you believe it in some ways look like Medievil.