Although the detailed background is unknown, it is supposed that in Muromachi period the clan was divided into two families, Shimonokuni (lower province) family and Kaminokuni (upper province) family and they were opposed to each other.
経緯の詳細は不明であるが、室町時代に入ると下国（しものくに）と上国（かみのくに）の二家に分かれ対立したと見られている。