It is impossible to know whether there is any truth in this story. But tea drinking certainly became established in China many centuries before it had even been heard of in the west. Containers for tea have been found in tombs dating from the Han dynasty (206 BC - 220 AD) but it was under the Tang dynasty (618-906 AD), that tea became firmly established as the national drink of China. It became such a favourite that during the late eighth century a writer called Lu Yu wrote the first book entirely about tea, the Ch'a Ching, or Tea Classic. It was shortly after this that tea was first introduced to Japan, by Japanese Buddhist monks who had travelled to China to study. Tea drinking has become a vital part of Japanese culture, as seen in the development of the Tea Ceremony, which may be rooted in the rituals described in the Ch'a Ching.