This is from an exhibit at the Suzhou museum last year. The topic of the exhibit is - "Restoration of Peace, the Four Faces of Han Dynasty Civilization", about archeological finds from Han Dynasty China near Suzhou.
The stones are made of a type of glass and not necessary "black and white" but blue and slightly yellow white. (or they might have been darker and lighter, but the colors degraded or changed over time). It was found in a tomb of a Han dynasty high royal prince. They didn't find a board, but a cloth with lines drawn on it and too degraded to know how many lines it was.
So it is possible that we didn't find many old game boards (or older than Han dynasty), not due to out of luck (or as some suggested Go was invented in Han dynasty), but because ancient players faced the same issue we are, and find it impractical to carry giant wood or stone slaps as gobans, and chose lighter materials like cloth or leather and draw grid on them as the board. Much cheaper and easier to produce.
