According to this record, it can be seen that Iwatate was in the same clan with the IWAMURA clan in Hekikai County in Mikawa Province, and also that Iwatate himself was a person from Sakyo.
この記事により、石楯が三河国碧海郡の石村氏と同族関係にあり、かつ自らは左京の人であったことがわかる。