that advanced all the way through the enemy lines was promoted to the lowest rank of officer. Others claim that the pawn, if the piece is available for promotion, is promoted to the piece initially positioned on the file on which the pawn stands, except if the pawn stands on the king's file, in which case it is promoted to a mantri. If the piece is unavailable, the pawn remains unpromoted on its square. Different versions of the latter rule have been recorded. In some instances, the pawn's promotion is based on the file on which it starts instead of the one on which it ends. Additionally, according to some sources, an immobile pawn on its last rank is promoted as soon as the appropriate piece becomes available. Chaturanga was introduced to the Middle East as shatranj around the 7th century. In shatranj, a pawn can be promoted only to a fers (equivalent to chaturanga's mantri). As chaturanga and shatranj spread to the western world and eastern Asia, as well as several other regions of the world, the promotion rule evolved. (See Regional games of the chess family section for more information.) After the queen gained its modern identity and abilities in the 15th century, replacing the farzin or ferz, some players objected to the fact that a king could have more than one queen via promotion. One old set of chess rules says, "A promoted pawn became a ferz, with the move of the queen." In Italy, in the 18th and early 19th centuries, a pawn could be promoted only to a captured piece; if none of the promoting player's non-pawn pieces were captured, the pawn remained inactive until a piece became available, whereupon the pawn immediately assumed that piece's role. Philidor did not like the possibility of having two queens; in all editions of his book (1749 to 1790), he stated that a promotion could only be to a piece previously captured. Lambe also stated this rule in a 1765 book. A player could thus never have two queens, three knights, three rooks, or three bishops. The restricted promotion rule was applied inconsistently. Jacob Sarratt's 1828 book gave unrestricted promotion. By Sarratt's time, unrestricted promotion was popular, and according to Davidson, it was universal by the mid-19th century. However, Howard Staunton wrote in The Chess-Player's Handbook, originally published in 1847, that Carl Jaenisch said that the restricted promotion