Jujutsu first began during the Sengoku period of the Muromachi period in 1532 and was founded by Takenouchi Hisamori, a military tactician and lord from Mimasaka Province. Takenouchi combined various Japanese martial arts which were used on the battlefield for close combat in situations where weapons were ineffective. In contrast to the neighbouring nations of China and Okinawa whose martial arts were centered around striking techniques, Japanese hand to hand combat forms focused heavily upon throwing, immobilising, joint locks and choking as striking techniques were ineffective towards someone wearing armor on the battlefield. The original forms of jujutsu such as Takenouchi-ryū also extensively taught parrying and counterattacking long weapons such as swords or spears via a dagger or other small weapon. In the early 17th century during the Edo period, jujutsu would continue to evolve due to the strict laws which were imposed by the Tokugawa shogunate to reduce war as influenced by the Chinese social philosophy of Neo-Confucianism which was obtained during Hideyoshi’s invasions of Korea and spread throughout Japan via scholars such as Fujiwara Seika. During this new ideology weapons and armor became unused decorative items, so hand to hand combat flourished as a form of self-defense and new techniques were created to adapt to the changing situation of unarmored opponents. This included the development of various striking techniques in jujutsu which expanded upon the limited striking previously found in jujutsu which targeted vital areas above the shoulders such as the eyes, throat and back of the neck. However towards the 18th century the number of striking techniques was severely reduced as they were considered less effective and exert too much energy; instead striking in jujutsu primarily became used as a way to distract your opponent or to unbalance him in lead up to a joint lock, strangle or throw. During the same period the numerous jujutsu schools would challenge each other to duels which became a popular pastime for warriors under a peaceful unified government, from these challenges randori was created to practice without risk of breaking the law and the various styles of each school evolved from combating each other without intention to kill.
The term jūjutsu was not coined until the 17th century, after which time it became a blanket term for a wide variety of grappling-related disciplines and techniques. Prior to that time, these skills had names such as “short sword grappling” (小具足腰之廻 kogusoku koshi no mawari?), “grappling” (組討 or 組打 kumiuchi?), “body art” (体術 taijutsu?), “softness” (柔 or 和 yawara?), “art of harmony” (和術 wajutsu, yawarajutsu?), “catching hand” (捕手 torite?), and even the “way of softness” (柔道 jūdō?) (as early as 1724, almost two centuries before Kanō Jigorō founded the modern art of Kodokan Judo).
Today, the systems of unarmed combat that were developed and practiced during the Muromachi period (1333–1573) are referred to collectively as Japanese old-style jujutsu (日本古流柔術 Nihon koryū jūjutsu?). At this period in history, the systems practiced were not systems of unarmed combat, but rather means for an unarmed or lightly armed warrior to fight a heavily armed and armored enemy on the battlefield. In battle, it was often impossible for a samurai to use his long sword, and would therefore be forced to rely on his short sword, dagger, or bare hands. When fully armored, the effective use of such “minor” weapons necessitated the employment of grappling skills.
Methods of combat (as mentioned above) included striking (kicking and punching), throwing (body throws, joint lock throws, unbalance throws), restraining (pinning, strangling, grappling, wrestling) and weaponry. Defensive tactics included blocking, evading, off-balancing, blending and escaping. Minor weapons such as the tantō (knife), ryofundo kusari (weighted chain), kabuto wari (helmet smasher), and kakushi buki (secret or disguised weapons) were almost always included in Sengoku jujutsu.
This information, and more about Jujutsu, can be found at the following Wikipedia link; http://en.wikipedia.org/wiki/Jujutsu