The Shima clan was considered to be a resident landholder around present-day Heguri-cho, Ikoma County, Nara Prefecture, and Kiyooki SHIMA was initially a shugo (military governor) of the adjacent province of Kawachi, and served the Hatakeyama clan who wielded their influence in Yamato Province as well.
島氏は今の奈良県生駒郡平群町周辺の在地領主であったと考えられており、島清興は、当初は隣国河内国の守護で、大和国にも勢力を扶植していた畠山氏に仕えた。