What keeps the secret of the SF from spreading? Basically everyone knows how it works and itís a common item in the Thirdersí supply chain, easily looted in the case of a failed expansion. I donít see how it wouldnít spread to other cultures given this much time. Sure they wonít switch over to mass production, but I can see even slightly more efficient farming (or slave labor) being used to have small SF crops as part of a luxury market.