The History of Shogi
Japan's take on the chess family, and the only major variant where a captured piece doesn't leave the game - it joins the side that captured it.
From India, by way of Southeast Asia
Like international chess and Xiangqi, Shogi ultimately descends from chaturanga, the ancient Indian war game that spread across Asia along trade routes starting around the 6th century CE. It reached Japan sometime before the 10th century, most likely by way of Southeast Asia and China, and was adapted over the following centuries into distinctly Japanese forms.
Early Japanese chess variants were considerably larger than the modern game - some historical forms, such as Dai Shogi and the enormous Tai Shogi, used boards of 15x15 squares or more with well over a hundred pieces per side. The 9x9, 20-piece version played today emerged as the standard by around the 16th century.
The Drop Rule's Origins
Shogi's defining feature - that a captured piece switches sides and can be dropped back onto the board - has no equivalent in chess or Xiangqi and sets it apart from every other game in this collection. Historians generally connect its emergence to the practice, common among Japan's warring samurai clans, of absorbing captured soldiers directly into the capturing army rather than treating them purely as casualties.
Whatever its exact origin, the drop rule transforms the game's character: material is almost never permanently removed, games rarely stall through simple material exchange, and an aggressive attack can be fed indefinitely by whatever the attacker has already captured.
A Living Professional Tradition
Shogi has supported a continuous professional tournament tradition in Japan since the Edo period (17th-19th centuries), when the Tokugawa shogunate funded a hereditary house system of professional players - a lineage that evolved into the modern Japan Shogi Association, founded in 1924.
Computer Shogi long lagged behind computer chess because of the drop rule's huge branching factor, but by the mid-2010s programs such as Ponanza had decisively defeated top professional players, prompting the same debates about human-computer play that chess had gone through a decade or two earlier.