It is written in the 'Wa; Wajin Kanren no Chugoku Bunken' (Chinese Documents about Japan and Japanese People) that Wajin (Japanese people) sent forth envoys seasonally to Lelang Commandery (an ancient county existed in the northern Korean Peninsula) and that Suisho, the king of Wa, dispatched 160 people (that is known as seiko meaning slave) as paying tribute (to the Han Dynasty) in 107, just after 50 years of Wa no Na no Kokuo no in (the golden seal unearthed in Japan that is curved the kanji that might signify the king of Wa).
「倭・倭人関連の中国文献」には倭人が季節ごとに楽浪郡に使者を遣わしてくることや、倭国王帥升が倭奴国王印のちょうど50年後の107年に入貢の際に160人もの人（生口、奴隷のこと）を送ったことが倭・倭人関連の中国文献の記録に残っている。