The Japanese msy have suspected it was there. The Koreans and Chinese might have made some wild-assed guesses along those lines, too.
Reposted from
The Alternate Historian
There are so many problems with this map, but are you seriously going to tell me the Portuguese were the first people to discover freaking Japan?
Comments
https://short-history.com/turtle-ships-766574ed5669
/s
Well played.