The Japanese combat techniques of Jujitsu date back at least 2000 years. The exact origins of Jujitsu are unclear, as most of it's history was only passed on in the oral tradition. The few early written references show that it's origins date back to mythology.
Jujitsu was formalized and most popular during the Edo period of Japan. This was the era of the Samurai. Jujitsu was the samurai's main set of combat techniques, after the sword that is. There have been many, many styles (or ryu) of Jujitsu throughout the history of Japan and more recently the rest of the world. Udo is the Korean adaptation of Jujitsu. Practicing this form develops coordination, muscle flexibility and helps to prevent arthritis and rheumatism in the joints.