Known. Two game boards were carved into bricks inside Han tombs.
The boards were found in Xi'an, in Shaanxi Province, at the Chang'an campus of Shaanxi Normal University. They are about 2,000 years old, from the Han dynasty (206 BC–220 AD). The game is called Liubo. One board was cut into a plain brick. The other was cut into a brick that already had a pattern. The tombs also held pottery, bronze mirrors, iron tools, and coins.
The full rules of Liubo are still a mystery, and scholars still debate whether the game led to Chinese chess.
https://www.ancient-origins.net/news-history-archaeology/liubo-game-boards-00103000