Pu’erh (pu’er) tea has been cultivated in China since the Han Dynasty (25-220 CE). This aged tea can be black or green depending on the leaves. It offers a rich and earthy flavor. Pu’erh was once banned in the United States, and today the cultivation remains a guarded secret by the Chinese. Black Pu'erh tea contains 60 to 70 milligrams of caffeine per cup and green pu'erh tea contains between 30 to 40 milligrams per cup.