A History of Poker

It is not clear exactly how poker came into existence. Some believe it came out of Chinese dominoes. There is some research to suggest that the Chinese transferred dominoes to thick paper, or cards, around the year 1000 A.D. Poker may also be a descendent of a card game called Ganjifa that was developed in India.

As-Nas in Persia
However, a seventeenth century Persian game called "As Nas" is probably the direct ancestor of Poker. As-Nas requires five players and a deck of 25 cards with 5 suits. It has great similarity to poker; two cards are dealt, followed by a round of betting; then two more cards and another round of betting. There is then a final card, and a last round of betting. The winner is the player with the highest ranked card.

French soldiers may have learned this game and brought it home, because the French developed a bluffing and betting game called "poque." Poque is said to be the first card game to use of a deck consisting of the modern suits.
A German game called "pochen" (or "pochspiel ") and an English game called "Bragg" are also related. (Pochen is the German word for "bluffing.") French settlers apparently brought poque to the New Orleans in the Louisiana Territory.

Modern Poker Came Out of New Orleans
It was in New Orleans and on the riverboats that called on the city that modern poker was developed. The early 19th century game was played with only twenty cards, using four suits from ace to ten. Each player was dealt five cards. It quickly became the most popular game on the Mississippi and Ohio riverboats, and traveled west by wagon and train. Stud poker, the draw, and the straight came about during the time of the American Civil War. The joker made was first used as a wild card in the last part of the 19th century.

The 52-card deck came into general use in the United States during the 1830s, and poker rules became standardized as rule books were developed. The game came into its own in the Old West. Poker soon overcame faro as the saloon favorite, as sharp players discovered how quickly they could get rich from it. Doc Holliday and Wild Bill Hickock, both of whom sometimes earned a living by playing cards, often had to relocate after poker disputes. Poker would be the last game Hickock played; on Aug. 2, 1876, in Deadwood, South Dakota, Hickock was shot by a man named Jack McCall. Wild Bill's cards, a two-pair hand of black eights and black aces, plus a fifth card, became known as the Dead Man's Hand.

From: http://www.gamblingorigins.com/gambling-history-poker.shtml