As the Kamakura bakufu, which served the Imperial court militarily, came to be called buke (military families), former Kizoku were called Bunkan, who served the imperial court in administrative affairs, or in other words, Kuge.
武力をもって朝廷に仕える鎌倉幕府が武家と呼ばれるようになると、従来の貴族は、政務一般で朝廷に奉仕する文官、すなわち公家と呼ばれるようになった。