There is a lot of choice in Mah Jongg playing cards. From the twenties till today. The western kind often have the same size as those of normal cards. For printers they were business as usual. Many manufacturers saw them as an affordable alternative.
Most Asian playing cards are narrow, rectangular and, supposedly, based on early Chinese decks made from bone or paper.
There was and is an endless number of brands on the market. Especially makers of cigarettes like to put their trademarks on them. And then there are cards with double use: for playing Mah Jongg or any other card game.