The robe of Kohuku originally had open sides, but since Yuwen Hu, an member of the Imperial Family in Northern Zhou, proposed to the government, this hoeki no ho was made (according to "Zuisho" (the Book of the Sui Dynasty), etc.).
胡服のうわぎは元来腋に開きのあるものだったが、北周の皇族の宇文護が襴をつけることを建言して以来、縫腋袍が成立した（隋書ほか）。