Despite the close cultural (for example, use of a pictograph system for writing), political (similar ideas about the nature and powers of the emperor) and economic (trade exchange ties) between early Chinese and Japanese societies, the two developed in different geographical--no surpise--and political environments.  Historians still disagree upon the exact reasons for that, but clearly  Japan's existence as an island society (partly insulated from migrating peoples and invaders by the sea) was much different than the Chinese experience (long borders with possible enemies on many sides).  Still, by the twelfth century or so, Japan had developed as a fairly stable, advanced society.
The Japanese samurai warrior was essentially similar to a medieval European knight, wielding similar weaponry, adhering to a strict moral code, fighting for religion and emperor and being a noble. The samurai also underwent a long period of training in preparation for his career.
Some recommended online lectures and websites:

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