The British Go association is citing gobase.org which is registered in the Netherlands, who is citing a historian named H.J.R. Murray. who said he read a 1983 Watanabe Hideo book where that guy says he saw a picture of a Go board excavated in China back in 1954, that is not possible to correctly carbon date since there was no reports of that excavation having any evidence of organic material collected to properly carbon date and no one has any photographs nor records to inspect of the actual excavation.
You are literally relying on a Chinese university tied to the Chinese government telling you “trust me bro we invented this” without providing the public any factual info to investigate.