How many suits are there in a mah jong tile set?

There are four suits in a mah jong tile set: characters (萬子, pinyin: wàn zi, lit. "ten thousands"), circles (筒子, pinyin: tǒng zi, lit. "tubes/cylinders"), bamboos (索子, pinyin: suǒ zi, lit. "strings/lines") and dragons (三元牌, pinyin: sānyuán pái, lit. "three origin tiles")