1364, St. Gallen, Switzerland. A local ordinance forbids dice, allows board games, and leaves the subject of cards untouched. This is often cited as the date before which cards could not have been known in Europe.
We know playing cards entered Europe in the 1370s because there are no references before this time, and suddenly they start appearing across the continent. In St. Gallen, an ordinance made in 1379 forbade the use of playing cards.