In 1247, when the Battle of Hoji occurred, a knot of Hidetane CHIBA, a family group of his clan was destroyed by the command of the bakufu (Japanese feudal government headed by a shogun), however, Yoritane was so young at that time that his family members, including his father's brother, Yasutane CHIBA, etc. took his duty.
1247年、宝治合戦がおきると、幕府の命令で一族の千葉秀胤の一派が滅ぼされているが、当時頼胤は幼かったため、父の兄弟である千葉泰胤ら一族の者が任を代行した。