I just stumbled onto an article written by Theo van Ees, in 2020, for the British Go Journal (#194, linked).
It’s apparently based on text written for Myongji University way back in 2005.
In Denmark’s National Museum in Copenhagen some playing pieces were exhibited around 1980. The stones were made of black and white glass, around 50 of each, varying in size, but looking like baduk stones. They were found in a Danish grave on Zealand dated 200-400 AD.
In a bog at Wimose on the island of Funen, Denmark, a grave from the same period was unearthed, containing parts of a wooden playing
board with 18 squares in a row. If we assume this board was square, it could have been a baduk board.
Nothing is known of the games that were played with these Danish finds (if they are for playing at all). Is it possible that baduk was known in this period? The finds of Chinese objects from the same period prove that some contact, however indirect, existed.
Some experts think that these game materials were used to play the game of hnefatafl. Tafl games are a family of ancient Germanic board games played on a chequered board with two teams of uneven strength. Versions were played across much of Northern Europe from at least 400 AD until it was supplanted by chess during the Renaissance.
Is it possible that the game equipment came from China, but that the way to play the game got lost somewhere on the journey and that only the way the pieces were placed was remembered?
I was reminded of this thread: