This is a list of Japanese clans. The old clans (gōzoku) mentioned in the Nihon Shoki and Kojiki lost their political power before the Heian period, during which new aristocracies and families, kuge, emerged in their place. After the Heian period, the samurai warrior clans gradually increased in importance and power until they came to dominate the country after the founding of the first shogunate.
Japan traditionally practiced cognatic primogeniture, or male-line inheritance in regard to passing down titles and estates. By allowing adult adoption, or for men to take their wife's name and be adopted into her family served as a means to pass down an estate to a family without any sons, Japan has managed to retain continuous family leadership for many of the below clans, the royal family, and even ordinary family businesses.