Phytoliths and biomolecular components extracted from ancient plant remains from Chang’an (Xi’an, the city where the Silk Road begins) and Ngari (Ali) in western Tibet, China, show that the tea was grown 2100 years ago to cater for the drinking habits of the Western Han Dynasty (207BCE-9CE), and then carried toward central Asia by ca.200CE, several hundred years earlier than previously recorded. The earliest physical evidence of tea from both the Chang’an and Ngari regions suggests that a branch of the Silk Road across the Tibetan Plateau, was established by the second to third century CE.
Earliest tea as evidence for one branch of the Silk Road across the Tibetan Plateau
by Houyuan Lu, Jianping Zhang, Yimin Yang, Xiaoyan Yang, Baiqing Xu, Wuzhan Yang, Tao Tong, Shubo Jin, Caiming Shen, Huiyun Rao, Xingguo Li, Hongliang Lu, Dorian Q. Fuller, Luo Wang, Can Wang, Deke Xu and Naiqin Wu
Tea (Camellia sinensis L.) is one of the most popular nonalcoholic beverages, consumed by over two-thirds of the world’s population for its refreshing taste, aroma, medicinal, and mildly stimulating qualities. The exact antiquity of tea is shrouded in Chinese myth. The first unambiguous textual reference to the consumption of tea as a beverage can be dated to 59 BCE during the Western Han Dynasty. However, its widespread popularity amongst both northern Chinese and people to the west such as Uighurs is generally attributed to the Tang Dynasty (7th–8th century CE). Previously the oldest physical evidence of tea was from China’s Northern Song Dynasty (960–1127 CE). It has long been hypothesized that tea, silks and porcelain were key commodities exported from the ancient Chinese capital, Chang’an, to central Asia and beyond by caravans following several transport routes constituting the network commonly referred to as the Silk Road, in use by the second century BCE. However, there are no records of tea having been carried along the Silk Road into Tibet, central Asia or southern Asia until the Tang Dynasty (618–907 CE). The Tibetan Plateau was then closely linked eastwards to central China through trade of tea and horses for Tibetan furs and medicinal plants. Although trade of millets already connected the Tibetan Plateau to lowland China more than 4000 calibrated years before present (yr BP), and barley cultivation and pastoralism expanded after 3600 yr BP, the emergence of historical patterns of commodity trade and habits of tea drinking along the Silk Road and in the Tibetan Plateau has remained poorly understood, due mainly to the poor preservation of plant leaves, and the challenge of identifying decayed tea remains in archeological samples.
Here, we present evidence from calcium phytoliths (calcium oxalate plant crystals), chemical biomarkers and radiocarbon dating from dried plant bundles from two funerary sites: the Han Yangling Mausoleum in Xi’an, Sha’anxi Province; and the Gurgyam Cemetery in Ngari district, western Tibet. Large modern reference collections are used to compare and contrast microfossil morphology and biomolecular components of these ancient remains to modern standards of tea and related plant species. Our study reveals that tea was drunk by Han Dynasty emperors as early as 2100 yr BP and had been introduced into the Tibetan Plateau by 1800 yr BP. This indicates that one branch of the Silk Road passed through western Tibet at that time.