Chess

Chess descends from chaturanga, a game that emerged in India roughly 1,500 years ago to represent an army's four divisions -- infantry, cavalry, elephants, and chariots -- which evolved into the modern pawn, knight, bishop, and rook. It was already played on an 8x8 board. Around the 7th century, the game reached Persia, where it became known as chatrang or shatranj; the Persians dropped the dice used in some earlier versions, turning it into a game of pure strategy, and renamed the pieces -- the king's Persian title, "Shah," is the root of both the word "chess" and the term "checkmate," from "Shah Mat."

Following the Arab conquest of Persia in the 7th century, chess spread through the Islamic world into North Africa, Sicily, and Spain, reaching wider Europe by roughly the year 1000.

Several rules considered fundamental today are relatively late additions. Pawns originally moved only one square at a time; the option to advance two squares on a pawn's first move was introduced in Europe in the 15th century to speed up play. That change created a loophole -- pawns could now slip past a square they would previously have been captured on -- which was closed by introducing en passant, alongside castling, as chess's rules modernized between roughly the 14th and 16th centuries.

These medieval and early-modern changes gradually converged into the rule set still used today, which the international federation FIDE now codifies and governs as the Laws of Chess for tournament and professional play worldwide.