Bushido formalized earlier samurai moral values and ethical code, most commonly stressing a combination of sincerity, frugality, loyalty, martial arts mastery and honour until death. Born from Neo-Confucianism during times of peace in the Edo period (1603–1868) and following Confucian texts, while also being influenced by Shinto and Zen Buddhism, allowed the violent existence of the samurai to be tempered by wisdom, patience and serenity. Bushido developed between the 16th and 20th centuries, debated by pundits who believed they were building on a legacy dating back to the 10th century, although the term bushido itself is "rarely attested in pre-modern literature". This ethical code took shape with the rise of the warrior caste to power at the end of the Heian period (794–1185) and the establishment of the first shogunate of the Kamakura period (1185–1333). It was developed further during the Muromachi period (1336–1573) and formally defined and applied in law by Tokugawa shogunates in the Edo period. There is no strict definition, and interpretations of the code have varied over time. Bushido has undergone many changes throughout Japanese history, and various Japanese clans interpreted it in their own way.