Contrary to what is universally believed and frequently repeated, the origins of tarot are neither obscure nor mysterious. During the mid-15th century it emerged fully formed from the intellectual, spiritual, and artistic ferment of the northern Italian Renaissance, a flowering branch germinated from the pre-existing stalk of the regular 52-card playing card deck.
Before there were tarot cards there were playing cards. These originally must have appeared in China, for it is there that paper was invented (See the International Playing Card Society's "History of Playing-Cards" at
http://www.pagat.com/ipcs/history.html). Cards and card games gradually spread from east to west, arriving in Europe from the Islamic world in the latter decades of the 14th century (Decker et. al.,"A Wicked Pack...," 29; Kaplan, Vol. II, 24) in the familiar form of a four-suited, 52-card pack with 10 numeral cards and three court cards in each suit. The Islamic quartet of suits -- cups, swords, coins, and polo sticks -- was altered in some places almost immediately, but retained in Italy and on the Iberian Peninsula (and by extension, eventually into Latin America) where it prevails even today. Only the polo sticks, whose purpose was not comprehended by Europeans of the time, were transformed into simple batons. This same suit arrangement was incorporated into the tarot deck.
The earliest known European print of people playing cards is a woodcut illustration for "The Romance of King Meliadus of Lennoys," a French work from the late 14th century. The clearly visible five of coins and deuce of batons in the hands of the players with their backs to us shows the persistence of the original forms and emblems of the Islamic cards, and in some cases even Arabic names were preserved for a time. For example, the city of Florence issued a decree in 1376 forbidding the game of naibbe (cards) (Kaplan, 1978, p. 24). The name derives from the title of the eight court cards in the Islamic deck representing the deputies of the four kings, who were called na'ibs.
Some aspects of the cards were altered almost immediately upon the deck's arrival in Europe, however, and the "Europeanization" of playing cards certainly began before 1400. One of the earliest changes was the transformation of the Islamic court cards, the King and his two deputies (for there were no queens at this early date) from abstract patterns to representations of people. The Islamic card makers were bound by the Muslim prohibition against the making of representational images from actually picturing a king and his subalterns, but the European card makers suffered no such limitations, and early on adopted a standard pictorial repertoire of representations of a king, a knight, and a foot soldier or servant for each suit.
By shortly after 1400 the explosive creativity of the Renaissance had extended to every aspect of artistic life, including playing cards. Fanciful new decks were produced which bore little resemblance to their Islamic ancestors, save that they had four suits and 52 cards. In Germany, several "hunting" packs appeared. These were elaborate, hand-painted and very expensive luxury items featuring suits of falcons, herons, hounds, and lures. In addition, every card was a picture card, not just the courts. This represented a new development not only in the presentation of cards, but also in the concept; these decks were not merely a game, but an exuberant celebration of a beloved sport and social activity as well.
Tarot cards were born out of a similar impulse, sometime between 1420 and 1440, in the Northern Italian cities of Ferrara, Milan, and Florence. The deck was altered by addition; the 22 trump cards are meant to express the philosophy we know as Neoplatonism, which was very abstract while at the same time humanistic. Four queens were added to the deck as well, making a total of 78 cards.
For a brief but thorough explanation of Neoplatonism, see Dr. Richard Hooker's essay at
http://www.wsu.edu:8080/~dee/REN/NEOPLATO.HTM.
The rest, as we say, is history, a subject which is all too frequently given a narrow latitude in discussions of subjects occult.