Recently, it has been noted that the record on "Azuma Kagami" (The Mirror of the East) states that originally they were one of the powerful samurai groups in the eastern part of Japan, Togoku Samurai, who were based in the area of Tonegawa River and also gokenin (an immediate vasal of the shogunate in the Kamakura and Muromachi through Edo periods)who belonged to an upper class like Tamai clan, Okabe clan, Nin clan and Takise clan from the Musashi-shichito Parties such as Yokoyama Party or Inomata Party (seven parties of samurai in Musashi Province).
近年では『吾妻鏡』によると、元は関東にいた御家人で、玉井氏・忍氏・岡部氏・滝瀬氏ら武蔵七党の横山党や猪俣党と並ぶ家柄であり、もともとは利根川流域に基盤をもつ東国武士の有力集団の一派だったという。