Mancala is among the oldest known games to still be widely played today. Chess is believed to have originated in northwest India, in the Gupta Empire ( 280–550), where its early form in the 6th century was known as "chaturaṅga" (), literally "four divisions" the military – infantry, cavalry, elephants, and chariotry, represented by the pieces that would evolve into the modern pawn, knight, bishop, and rook, respectively. "Chaturanga" was played on an 8×8 uncheckered board, called "ashtāpada". Shogi was the earliest chess variant to allow captured pieces to be returned to the board by the capturing player. This drop rule is speculated to have been invented in the 15th century and possibly connected to the practice of 15th century mercenaries switching loyalties when captured instead of being killed.