Mid 19th century.: of U.S. origin; perhaps related to German pochen ‘to brag,’ or Pochspiel ‘bragging game.’
The following story is not verified, but it sounded good... could be the stuff that legends are born of.
The Cherokee Indians invented Poker in 1764 as a means to steal money from the White Man. After all of the Redskins were killed in the War of 1812, Napoleon Bonaparte took their stockpile of American cash and, legened has it, they opened the first casino.
As an interesting point of fact, due to his blood oath with Satan, Napoleon had to open the casino near a gate to hell. Atlantic City, NJ was born a year later. "Atlantic City" is French for "The Devil's Taint."