Jeson Mor

How Jeson Mor is played

Jeson Mor, “nine horses”, is a Mongolian game of knights on a 9 × 9 board.

The board and the knights

Nine files, a to i, and nine ranks. Each side has nine knights on its first rank, Red on rank 1 and Green on rank 9, told apart by the colour of their bases; Red moves first. A knight leaps as in chess: two squares in one direction and one to the side, over anything in between. It captures an enemy knight by landing on it.

The centre

The square in the middle, e5, is marked. A knight on e5 can still be taken. If it is still there when it is your turn again, moving it away from e5 wins the game. A knight that captures on e5 holds the square for its side and must survive the reply too.

Winning and draws

Taking the opponent’s last knight wins, and so does leaving the opponent without a move. The same position three times and fifty moves each without a capture are draws.

Where the rule comes from

The only older description, Assia Popova’s of 1974 after Namžildorž, says just that each player tries to reach the centre. Read literally, the first player would reach e5 on the second move, before the other can stop it. David Pritchard supposed that the square had to be held for a turn; Wikipedia’s wording, leaving e5 after the reply, is played here. Fairy-Stockfish ends the game one move earlier, as soon as the reply has not taken the knight.

The story

Mongolia · a Mongolian game, recorded in 1966

When and where

Jeson Mor, “nine horses”, is a Mongolian game. It is known from the Mongolian scholar Namžildorž’s books on the games of Mongolia (Ulaanbaatar, 1963 and 1966), which the ethnographer Assia Popova analysed in 1974. She counted it among the race games: each side has nine horse figurines on a board of 9 × 9 squares, they leap like the knights of chess, and each player tries to reach the centre square first.

How it changed

Popova gives only the goal. She describes it next to aralzaa, where three horses a side race across a 3 × 3 board to the other’s start without capturing; in Jeson Mor the horses may also capture, though the capturing is, in her words, secondary to the race. Taken literally, reaching the centre would win on the first player’s second move, so David Pritchard (1994) supposed that a knight had to hold it for a turn. Wikipedia and the engine Fairy-Stockfish made that the rule: the knight must stand on e5 through the opponent’s reply, and it wins when it leaves.

Today

Programs such as Fairy-Stockfish and the Ludii game system play it, and PyChess offers it online.

Did you know?

Popova writes that the horses of aralzaa are carved in wood like chessmen, and Jeson Mor uses the same figurines. In his encyclopedia David Pritchard filed it among the games with “fixed goals in neutral territory”.

Sources: A. Popova, Études mongoles 5 (1974) · D. B. Pritchard, The Classified Encyclopedia of Chess Variants (2007) · Wikipedia

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Chess and variants

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The chess family

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• Byzantine chess · Shatranj on a round board: the rook circles, pawns never promote.
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• Manchu chess · Red’s lone chariot moves as horse and cannon too, against a full army.
• Jieqi · Xiangqi with the pieces face down: each is revealed by its first move.
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• Shogi · Japanese chess: captured pieces return to the board on your side.
• Minishogi · Shogi on a 5 × 5 board: six pieces a side, short and sharp games.
• Chu shogi · Japan’s great shogi on 12 × 12: no drops, and a lion that moves twice.
• Tori shogi · Bird shogi on 7 × 7: a phoenix, quails and swallows, with drops.

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