The Bassai (To Penetrate a Fortress) kata are believed to have been designed to complement each other as the first, Bassai Dai, (Dai means major/large) represents getting into a fortress and the second, Bassai Sho, (Sho means minor/small) represents getting out again.There are many versions of these kata practiced in various styles and while the origins within martial arts history are obscure, there is a 400 year old silk drawing which supposedly depicts an early version of Bassai Dai.