The history of the Japanese martial arts and JuJitsu can be traced over 2500 years.
Like many countries, Japan had a turbulent feudal history. Historically Japan had an emperor. During the Yamato period (approx 210-700 AD) they formed a power structure and system based around the emperor, with a largely rural and agricultural society. Armies were controlled centrally and were loyal to the Emperor. As Emperors died and were succeeded, the capital and it’s structures would be moved to the new Emperors location.
However, the end of the Yamato period, and specifically beginning of the Heian Period (784 AD) saw the breakdown of centralised government and armies. While the Emperor often remained a figure head, power was lost to local warlords who recruited and trained their own armies. The real formation of the Samurai and their teaching started to form out of necessity. Armed and unarmed combat systems were developed and refined, with this collection of techniques allowing the Samurai defend themselves and enforce law.
As with all Japanese martial arts, there is a huge array of historical divergence to this art. There have been many periods of development, often caused by legal issues and technological breakthroughs. This gradual but constant legal change and social pressures cause the Bushido to evolve. For example, the strict laws which were imposed by the Tokugawa shogunate to reduce war were particularly influential. They resulted in the incorporation of grappling and locking. Similarly, the technologies associated with armour and its strength reduced any emphasis on direct striking, and thus moved the art to incorporate and focus on precise attack of weak points often correlating to those weak points in armour.
While the Bushido has been around for thousands of years, the name JuJitsu was not coined until the 17th century.
Another notable example of this was the Meiji Restoration (1868), where martial arts and many weapons were completely banned. Upon the later decriminalisation of martial arts, Jujitsu was studied and formed the basis of many arts, from Karate to Judo. Even now, Jujitsu still evolves and influences, as everyone from police to modern wrestlers use and contribute new and techniques which are absorbed into to the Bushido.