It originates from the samurai moral code stressing frugality, loyalty, martial arts mastery, and honor unto death. Born from Neo-Confucianism during times of peace in Tokugawa Japan and following Confucian texts, Bushido was also influenced by Shinto and Zen Buddhism, allowing the violent existence of the samurai to be tempered by wisdom and serenity. Bushido developed between the 9th and 20th centuries and had wide influence across the whole of Japan. Under the Tokugawa Shogunate, aspects of bushido became formalized into Japanese feudal law. Bushido, then, is the code of moral principles which the samurai were required or instructed to observe. More frequently it is a code unuttered and unwritten. It was an organic growth of decades and centuries of military career.