During the Middle Ages, the Abe clan transferred the post of Ommyo-no kami (the head of the Ommyoryo (Bureau of Yin and Yang)) by succession while the Kamo clan, who held the post of Ommyo-no suke (deputy minister of Ommyoryo), played a subservient role.
中世には安倍氏が陰陽寮の長官である陰陽頭を世襲し、賀茂氏は次官の陰陽助としてその下風に立った。