His pedigree record is unknown, but according to "Seishi Kakei Daijiten" (a Large Dictionary of Japanese Surnames) written by Akira OTA, there is a place-name called Iwa-go (Iwa village), Shiso County, Harima Province in "Wamyoruiju-sho" (Kango-Japanese Dictionary).
系譜未詳の人物であるが、大田亮著の『姓氏家系大辞典』によれば、『和名類聚抄』に播磨国完栗郡伊和郷の地名がある。