Musashi Province was a buffer zone between the two powers: MINAMOTO no Yoshitomo based in Sagami Province and his younger brother MINAMOTO no Yoshikata who advanced into Kozuke Province.
武蔵国は、相模国を本拠とする源義朝と、上野国に進出してきたその弟・源義賢という両勢力の緩衝地帯であった。