Originally, they were court nobles who served the Imperial Family, but they moved to Kamakura upon Imperial Prince Munetaka's installation as Shogun during the late Kamakura Period, after which they became warriors.
元々は、天皇家に仕える公家であったが、鎌倉時代後期、親王の将軍就任に従って鎌倉へ下向してのちに武士となった。