One of the widely played variants of Shatranj was Shatranj al-husun, or Citadel chess. The description here is based on the description in Gollon's book; in the books of Pritchard and Murray a description of the game can also be found. (Actually, most probably, all other sources base their information on Murray's description.) The game is played on a 10 by 10 board, which has four additional fields: the citadels. There are several different opening setups, we give here only one; for the others we refer to the other sources mentioned above. The four fields at the corners are the citadels.
Players have the usual pieces of Shatranj plus two war machines, or dabbabah's, and two extra pawns.
The opening setup is the following:
A 10 by 10 board is augmented with four extra, empty squares, diagonally adjacent to each of the four corners. So, squares a2-a11; b1-k1; b12-k12; l2-l11 do not exist.
King f2; General g2; Rook b2, k2; Knight c2, j2; Elephant c2, i2; War machine d2, h2; Pawn b3, c3, d3, e3, f3, g3, h3, i3, j3, k3.
King f12; General g12; Rook b12, k12; Knight c12, j12; Elephant c12, i12; War machine d12, h12; Pawn b11, c11, d11, e11, f11, g11, h11, i11, j11, k11.
The pieces move as follows:
King, knight (actually: Horse), rook (actually: chariot, called: rukh) move as in orthodox chess.
The general moves one square diagonally.
The elephant moves exactly two squares diagonally, and can jump the intervening square.
The pawn (actually: soldier) moves as a normal pawn from FIDE-chess, but does not have the possibility of a first double move. Pawns promote to generals, when reaching the last row.
The war machine or dabbabah moves as a bishop from FIDE-chess.
When a king reaches a citadel at the opposite side of the board, the game is drawn. A player wins the game, by mating or by stalemating his opponent.
This game has - in contrast to Shatranj and some of its variants, no `bare king' rule, i.e., the game continues normally when one player has lost all its pieces but his king.