Also, because he grew up in his mother's hometown of Soma-gun County (Shimosa Province) he is said to have been named "Soma Kojiro"; however, this does not mean that Soma-gun County was in his sphere of influence, as the actual centers of power are considered to have been in Toyota-gun County (Shimosa Province) and Sashima-gun County (Shimosa Province).
また、母の出身地である相馬郡(下総国)で育ったことから「相馬小次郎」と称したとされているが、これは相馬郡に勢力があったということではなく、実際の勢力範囲は同国の豊田郡(下総国)・猿島郡両郡であったと考えられている。