Puerh History - Pu-erh.Net

„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.“

„Mushroom shaped tea appeared in 1912. It was invented at that time in order to prevent the tea from going mouldy during the transportation. It was produced in Xia-Guan and Fo-Hai (two cities in south China) with the trademark "Bao-Yan". The production was then stopped in 1966. In 1986, the production was resumed due to the request of Buddhists in Tibet.“