Analysis carried out by scientists on leaf buds found in burial pits around two ancient tombs has proved that they are from the tea plant.
One tomb in Xi’an in Shaanxi province was built for Jing Emperor Liu Qi, who died in 141 BC; the other is in the Ngari district of western Tibet and probably dates back to 200 AD. Archaeologists found the tea buds along with millet, rice, and spinach-like leaves and compared the chemistry of the buds to those of modern tea.
They found caffeine and L-theanine (which only exists in the Bay Bolete mushroom and Amazonian Guyusa) thus proving that the old buds were indeed tea. The tea plant does not grow in the regions where the tombs were found and must have been imported from elsewhere. The fact that the tea was found mixed with other vegetables and grains suggest that it was probably being consumed as a food at that time rather than as a beverage.