The dictionary of common folk culture, (c. 1210–1221), a collection based on the two works and , describes two forms of shogi, large "(dai)" shogi and small "(shō)" shogi. These are now called Heian shogi (or Heian small shogi) and Heian dai shogi. Heian small shogi is the version on which modern shogi is based, but the "Nichūreki" states that one wins if one's opponent is reduced to a single king, indicating that drops had not yet been introduced. According to Kōji Shimizu, chief researcher at the Archaeological Institute of Kashihara, Nara Prefecture, the names of the Heian shogi pieces keep those of chaturanga (general, elephant, horse, chariot and soldier), and add to them the five treasures of Buddhism (jade, gold, silver, katsura tree, and incense).