Everything indicates that the origin of the letters is located in the times of Imperial China. Later it arrived in Medieval Europe around the 14th century and it was the aristocracy and the bourgeoisie who began to play card games.
As the cards in the deck spread to the Germanic countries, the four-suit theme was retained, but hearts appeared in one of the suits; also at this time you can find figures of leaves, bells and acorns.
When card games began to be enjoyed in England, card makers adopted the French design but modified some details, and the suits in the deck were renamed clubs, hearts, diamonds, and spades.