144 tiles (138 without bonus tiles)
There is good evidence from Chinese researchers that Mahjong originated in the provinces of Kiangsu, Anhwei and Chekiang near Shanghai because no records of Mahjong are found in any other part of China before 1900.
During the Sung Dynasty (960-1279 AD) there is history of a game called "Ya P'ai" which is played with 32 cards made of either wood or ivory, and are oblong in shape similar to the present day Ma Jong tiles. During the Ming Dynasty (1368-1644 AD) a game called "Ma Tiae" (Hanging Horse) was invented. This game was played with 40 paper cards similar in appearance to the cards used in the game Ya P'ai.
These forty cards were numbered 1 to 9 in four different suits along with four additional flower cards are quite similar to the numbering of Mahjong cards today. It is thought that roughly around 1850 AD in the city of Ningpo two brothers had developed Mahjong from the earlier game of ma tiae.
The introduction to the western world is thought to have begun with two brothers named White, who introduced Mahjong to the English clubs of Shanghai in the early 1900's, where it quickly gained popularity among the foreign residents.
Mahjong first hit Japan in 1907 and the Japan variant emphasises going Mahjong the quickest.
Mahjong was taken to America by Joseph P. Babcock who began importing sets in bulk to the USA in 1922. At that time Babcock was the Soochow representative of the Standard Oil Company. It wasn't however until two years later a lumber merchant from San Francisco named W. A. Hammond formed the Mahjongg Sales Company of San Francisco and began importing large quantities of sets.
M.C. Work, Robert Foster, Joseph Babcock, Lee Hartman, and J.H. Smith. All of these gentlemen had previously written their own book of rules, and they were employed by the American Official Laws of Mah-Jongg to create a rule set published in 1924. Following this a number of variations with increasing numbers of special hands followed.
In Britain the classical rules were used. The Queens Club Rules and the rules laid down in a booklet by C.M.W Higginson. Both of these were based on Chinese variants. Currently the British Mahjong Federation publish a rule set that is close to the classical rules. The main differences are that only one Chow is allowed per person per round and that a few additional special hands are allowed.
Chinese Classical – see above – variation by Babcock when bought to the west in 1920’s (simplified/commercialized Classical Chinese) – all players score.
Western (Classical or "Vanilla") – Similar to Chinese Classical. All players earn points (not only the winner). Goulash" may be played.
American – Jokers added, flower/season used as extra tiles for ponging. Score by looking it up on the tile. Only winner paid.
Hong Kong old style - Score by counting doubles, then convert to points. Only the winner is paid.
Japanese Classical – Flowers not used. Only the winner is paid.
Japanese Modern - Base points times fan
Malaysian / Singapore - May use a large number of tiles with a variety of flowers which can be used to capture other players' flowers.
Taiwanese - Taiwanese Mahjong is played with larger 16 tile hands!
Though variants of Mahjong games are being introduced time and again, there are only four variations that are widely accepted among players:
Chinese Classical Mahjong is known to be the oldest version of the game. This was the first Mahjong game version introduced in America and became the model for many forms that were created since then.
Cantonese Mahjong also goes by the name of Hong Kong Mahjong game. It is the most common variety and only posses slight differences as compared with the classical version.
Japanese Mahjong is the most commonly used form of Mahjong game among Japanese. This includes rules and scoring guidelines that have been standardized and used in video games. The riichi and dora mark the highlights of the game.
Western Classical Mahjong is the version that was revised from the Chinese classical and was introduced in America. Babcock made the changes in this American version in 1920s. And his version was adopted and recreated by players in the later years.
British variation - The Queens Club Rules and the rules laid down in a booklet by C.M.W Higginson.
These are mainly Mahjong websites as that’s where I search most! Also added some odd comments!
 The Pocket Guide to MAHJONG (1924) – from http://www.garethjmsaunders.co.uk/mahjong/
 Berrie Bloem's Mahjongg - http://www.mahjongg.com/ - alternative – western American influenced – also great bit on symbolism of tiles
 http://www.xs4all.nl/~korntner/mahjong/nanette/nan_notes.html, Nannette Pasquarello
 Anne_J, http:// home.worldonline.dk/anne_j/uk/rules.htm - Western rules adapted from Chinese classical rules. (contains “only possible” as taking into account already passed tiles).
 http://www.mahjongmuseum.com/tradrule.htm#draw - classical
 http://spotlightongames.com/chart/mj.html - Chinese Classical
 mj_early_scoring.txt - claims to be earliest classical scoring
 http://www.cs.utk.edu/~clay/mahjongg/rules.html - incomplete
 http://www.msoworld.com/mindzine/news/orient/mah_jong/overview_intro.html - mistakes - text exactly as [3, 5]
 http://www.geocities.com/SiliconValley/7956/mj.html - same text as other sites
 http://www.soyouwanna.com/site/syws/mahjong/mahjong.html - American version, has the order of players going the wrong way compared to normal.
 http://www.free-conversant.com/mindspill/156/enclosure/Mahjong%20summary.pdf – also has players US / opposite way to normal
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