In the late 13th to the early 17th centuries, during Japan's war torn feudal period, ninjutsu grew sophisticated in the cloak and dagger arts. Children born into ninja clans were trained as spies early on and continued to train for the rest of their life. Never appearing in public without a disguise, the ninja kept his name, objectives, and techniques a secret even to the point of death. Because of their early training, ninja could run faster, jump higher, swim further and faster than normal men. . Since staying alive depended on secrecy, a man was born a ninja and died one. If he ever tried to leave the clan, he was hunted down by other agents and killed.