In the northern dynasty , kobun learning of later han was practiced , and " zhouyi ," " shujing ," " mao shi ," and ' sanrai ' honored annotations by jo gen , " chunqiu zuoshi zhuan ," the annotation by fukken of later han , and " shunju kuyo-den ," the annotation by ka kyu of later han . 北朝では後漢の古文学が行われ、『周易』・『書経』・『毛詩』「三礼」は鄭玄注、『春秋左氏伝』は後漢の服虔(ふっけん)の注、『春秋公羊伝』は後漢の何休の注が尊ばれた。