Let’s start with a definition of terms. Bo means „staff“ and generally refers to a weapon about six shaku in length, or six feet, or thereabouts, and one sun in diameter.1 Jo, meaning „stick“ or „cudgel“ are shorter weapons and do not have a standard length or diameter, as size depends on the particular ryu. Both the bo and jo lack a cutting edge or sharpened point, so they are classified as impact weapons and derive their effect from the force delivered by accurately hitting or thrusting at a particular target. It is likely that the staff was developed systematically as a weapon before the stick, due to the advantage of longer reach. The stick began to be used in combat as technical sophistication and experience with the weapon increased.