However, there is no sufficient evidence to prove it, and the remaining genealogies of the Yagyu clan still have to be studied in detail; some historian says that they originated from the Hata clan like the Hattori clan.
しかし確証性が乏しく、柳生氏の系譜の比較考証が考慮する必要性がある（あるいは服部氏同様に秦氏の系統ともいわれる）。