I've heard that in Tang dynasty Pu-Erh was important in order to keep the peace in remote areas partially because it was consumed as a substitute for fresh vege

I've heard that in Tang dynasty Pu-Erh was important in order to keep the peace in remote areas partially because it was consumed as a substitute for fresh vegetables in areas where one could not grow them. Consuming tea as thick soup to me suggests the idea that maybe tea was used in that way even back in Han dynasty (I'm sure that whether this is correct or not would be obvious to a historian, which I'm not). Do you have any recommendations for a curriculum of sort for tea history?