Heian dai shogi

Heian dai shogi (Japanese: 平安大将棋 'Heian (Era) large chess') is an early large board variant of shogi (Japanese chess) as it was played in the Heian period. The same 12th century document which describes the Heian form of shogi also describes this variant, where it is simply known as dai shōgi (大将棊). It is retrospectively named Heian dai shogi to distinguish it from the later dai shogi played on a 15 × 15 board.