Thus, it was considered the preceding genealogies of the Chiba clan edited in earlier days had consisted of errors; when "CHIBA Taikeizu" (the Complete CHIBA clan genealogy) was compiled in Edo period, Tsunetane and Tokitane were described as brothers and the sons of Naritane.
そこで江戸時代に『千葉大系図』が作成された際に先行系図に誤りがあるとして胤綱と時胤を兄弟として父を成胤とした。