Pu-erh tea

„This process was first developed in 1972 by Menghai Tea Factory and Kunming Tea Factory] to imitate the flavor and colour of aged raw pu-erh, and was an adaptation of wet storage techniques being used by merchants to falsify the age of their teas. Mass production of ripened pu'er began in 1975. It can be consumed without further aging, though it can also be stored to "air out" some of the less savoury flavors and aromas acquired during fermentation.“

„Yunnan Tea Company standardized the trade number for Pu Erh Tea in 1976 for the purpose of export. Each bingcha has 4 digits: the first 2 digits indicate the manufacturing year, the third digit indicates the leaf grade, the last digit indicates the tea factory (e.g. Kun-Ming 1, Meng-Hai 2, Xia-Guan 3, Pu Erh 4). The loose-leaf tea has 5 digits with the third and fourth indicating the class level of raw materials. Examples of early trade numbers for Puerh Tea are 7452, 7562, 7572, 75671, 76563.“