It is believed that they were given to powerful clans to show their ranks and official duties as they began solidifying their positions in relation to Royal Family when Yamato sovereignty became stable.
ヤマト王権が成熟し、大王家を中心として有力氏族の職掌や立場が次第に確定していく中で、各有力者の職掌や地位を明示するために付与されたと考えられている。