Estimated to be formed around 350 A.D., tea bricks have become a part of Chinese and European culture throughout the ages. Before tea bricks where introduced to Europe, tea bricks were used in China as a form of currency, food, and medicine. From the 9th century on through the 20th century, tea bricks were classified into five different quality categories of value. All the bricks, even to this day, are scored on the back with indentions to allow for easy breakage off the larger block. Read more here.