As seen in the beginning of the selection of Asuka Kiyomihara Code (the legal code of Japanese ancient state) in 680 as well as in the edict of Yakusa no Kabane, it was one of the policies to reform the old clan system and to create the bureaucracy which was able to promptly respond to a new national regime.
680年（天武10）飛鳥浄御原令の選定を開始したことに見られるように、また、八色の姓の詔にも見られるように、旧来の氏族制度を改革し、新しい国家体制に即応出来る官僚制創造の政策の一環であった。