Some form of the game of Chaturanga, the ancestor of both chess and shogi, reached Japan by the 9th century, if not earlier,[1] but the earliest surviving Japanese description of the rules dates from the early 12th century (c. 1120, during the Heian period).
This description does not give enough information to actually play the game, but this has not stopped people from attempting to reconstruct this early form of shogi.
This article outlines a fairly complete set of rules that can make the game playable in modern times.
Two players, Black and White (先手 sente and 後手 gote), play on a board ruled into a grid of 8 or 9 ranks (rows) by 8 or 9 files (columns).
The characters inscribed on the backs of the pieces to indicate promoted rank may be in red ink.
(The traditional terms 'black' and 'white' are used to differentiate the sides during discussion of the game, but are no longer literally descriptive.)
The knight can jump, that is, it can pass over any intervening piece, whether friend or foe, with no effect on either.
The lance can move any number of empty squares along a straight line, limited only by the edge of the board.
If an opposing piece intervenes, it may be captured by moving to that square and removing it from the board.
Betza's funny notation has been included in brackets for easier reference.
In practice this rarely happens, as a player will resign when checkmated, as otherwise when loss is inevitable.
There are two other possible (but fairly uncommon) ways for a game to end: repetition (千日手 sennichite) and impasse (持将棋 jishōgi).
If the same position occurs four times with the same player to play, then the game is no contest.
The game reaches an impasse if both kings have advanced into their respective promotion zones and neither player can hope to mate the other or to gain any further material.
The method used in English-language texts to express shogi moves was established by George Hodges in 1976.
The first letter represents the piece moved: P = pawn, L = lance, N = knight, S = silver, G = gold, K = king.