Munemoto HONJO, the original forefather of the Matsudaira (Honjo) clan, was a half-brother of Keisho-in, the biological mother of the fifth shogun Tsunayoshi TOKUGAWA, and was therefore promoted to daimyo (feudal lord), and from Mototoshi MATSUDAIRA, who was the child of Munemoto, the family was allowed to call itself the Matsudaira clan.
松平（本庄）氏の家祖・本庄宗資は第5代将軍・徳川綱吉の生母・桂昌院の異母弟ということで大名に取り立てられ、宗資の子松平資俊より松平氏を許された。