Even after that, there was 'Goin' (the seal of pseudonym) used by the Buddhist monks who came to Japan from the Southern Sung Dynasty to Japan, which proves that seals did not stop being used to prove official status.
その後も公的証明に印が使われなかったわけではなく、南宋からの渡日僧が用いた「号印」という印が存在する。