jts wrote:It's also important to remember that in even games, ancient Chinese go was played with diagonal fuseki. I'm not sure when they stopped. But in the seventh century, it's not as though there was free-placement versus fixed-placement, there were two different kinds of fixed placement.
Yes. It is possible that Chinese style diagonal placement baduk would have been played along with sunjang placement baduk. It is reported that
Kim Ok-kyun (Honinbo Shuei's Korean friend---there are some interesting stories in John Fairbairn's Shuei book about him and the Driftwood Go Board; the report is not from John's book though) claimed that Chinese style placement was popular in the late 18th century, when gambling on baduk became all the rage and sunjang baduk came back into style because it sped up the games compared to Chinese placement baduk.
History often is murky and there are often many gaps in the historical record. I would say that the argument that only sunjang baduk (and no other variant) was played in Korea until the 20th century is an awfully strong one to make given the nature of these things.