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.“

„Smoothness, Softness and Character of Puer Tea
Puerh tea is a type of post-fermented tea. When stored in the correct environment the tea, over time will change, hence - post-fermented. Due to this, the bitterness and astringency will slowly transform. The flavour will soften, become more mellow, rich, the character will become more rounded and mature.“