The Emperor Yongle, who was accused of being a usurper soon after his ascension, welcomed the envoy from the 'outer barbarians' as an opportunity to prove his virtues, and gave Yoshimitsu the seal of 'the king of Japan' (Nihon-kokuo no in) and a tally (a certificate to show that the ship was lawfully registered by the Ming), which was necessary for trading.
即位して間もなく、簒奪者との謗りも受けていた永楽帝は、「外夷」からの使節の到来を自らの天子としての徳を証明するものとして喜び、義満に「日本国王之印」と通交に必要な勘合符を与えた。