Tai shogi (泰将棋 "tai shōgi" or 無上泰将棋 "mujō tai shōgi" "grand chess", renamed from 無上大将棋 "mujō dai shōgi" "supreme chess" to avoid confusion with 大将棋 "dai shōgi") is a large-board variant of shogi (Japanese chess). The game dates to the 15th century and is based on earlier large-board shogi games. Before the discovery of taikyoku shogi in 1997, tai shogi was believed to be the largest playable chess variant, if not board game, ever. One game may be played over several long sessions and require each player to make over a thousand moves. It was never a popular game; indeed, a single production of six game sets in the early 17th century was a notable event.