This is recorded in what could be called the encyclopedia of tea, the 8th century 'Cha jing[The Classic of Tea]' written by Lu Yu(?-804). We know about tea in the Tang Dynasty from this 'Chajing'. Firstly, unlike today, the tea was preserved by being pressed and dried into hard bricks(dancha). The brick was then roasted over a fire and ground in a chagen mortar which was similar to a yagen mortar used for grinding medicine. The powder was put in hot water and drunk with salt and so on, as flavouring.
The 'Chajing' also tells us about the history of tea and about utensils, but the thing that attracts people's notice is that tea is said to be suitable for someone who is cultivating frugality. Here frugality means moderation. In other words, Lu Yu is saying in the Chajing that tea is a culture of the mind. In the Sung Dynasty that followed the Tang, tea had spread throughout China. The government created a monopoly on tea which became an important source of revenue for the government and therefore an important industry. Then in the Ming Dynasty there was a change from powdered tea to leaf tea, the current style of Chinese tea.