The roots of Ju-Jitsu can be traced at least as far back as the fifteenth or sixteenth century in Japan.
Samurai warriors wore protective armour and they fought using weapons. There was little need for unarmed techniques unless the two warriors were so close together that swords or daggers could not be used or there was a need to capture rather than kill the enemy. Methods were devised which would exploit the joints in the armour to allow the opponent to be subdued.
The opportunities for armed warfare were restricted and armoured fighting became obsolete. The techniques developed earlier were changed to meet the new needs for dealing with unarmoured opponents.
As the restrictions continued more schools were opened which taught common people unarmed combat. Commoners were not allowed to carry weapons and so the techniques were refined still further. Refinements to techniques continue today with all martial arts. One of the most modern forms of Ju-Jitsu, Gracie Ju-Jitsu has been developed in Brazil. Gracie Ju-Jitsu concentrates on taking an opponent to the ground and has adapted many traditional Ju-Jitsu techniques to work on the floor where differences in size and weight can be minimized.