Tea: from the hills of southern China to the world's cup

The tea plant, Camellia sinensis, was not domesticated once. A genetic study of tea from China and India (Meegahakumbura et al. 2018) found three separate lineages, each brought into cultivation on its own: China-type tea, a Chinese Assam type and an Indian Assam type. The authors propose southern China as the home of China-type tea and western and southern Yunnan for the Chinese Assam type, but they say the exact origin is unknown because wild populations have not survived. They estimate that the Chinese and Indian Assam lineages split about 2,770 years ago. Their own paper gives two figures for the start of domestication, over 3,000 and over 4,000 years ago, which shows how uncertain the date still is.

The oldest physical tea yet found comes from a tomb. In 2016 a team led by Houyuan Lu identified tea leaves in a pit of the Han Yangling mausoleum near Xi'an, built for Emperor Jing of the Western Han, who died in 141 BCE. They used three independent tests: the shape of microscopic crystals in the leaves, and the presence of theanine and caffeine. The same team found tea in a vessel at Gurgyam cemetery in Ngari, western Tibet, from the second or third century CE. They read it as evidence that tea travelled along a branch of the Silk Road over the Tibetan Plateau long before the "Tea Horse Road" through Yunnan, which they date to the seventh century. The first unambiguous written reference to tea as a drink, they note, dates from 59 BCE.

How tea was prepared changed with the dynasties. Under the Tang (618-907) tea drinking spread north from southern China, and in 770 the court set up an office to produce tea for the imperial household. In the middle of the eighth century Lu Yu wrote the Chajing, the Classic of Tea, which the Flagstaff House Museum of Tea Ware in Hong Kong treats as the most important single influence on Chinese tea culture. Tea was then traded and stored as pressed cakes. Breeders were already selecting cultivars from about the eighth century.

Under the Song (960-1279) tea became a national drink, taken at every level of society. The cake was ground to powder and put in a bowl; hot water was poured on and the mixture whisked until it frothed. Museum curators call this the whipped-tea method. In 1391 the first Ming emperor banned the making of tea cakes for tribute, and loose leaves made from young buds took their place. Ewers and whisking bowls went out of fashion, and new vessels better suited to steeping loose leaf appeared. The museum dates the beginning of the teapot to this change.

Tea also moved inland as a trade good. Lu and colleagues describe a long exchange in which central China sent tea to the Tibetan Plateau for horses, furs and medicinal plants. A popular account says tea first reached Tibet in the dowry of the Tang princess Wencheng in the seventh century; the Gurgyam find suggests tea was there several centuries earlier.

Tea reached Japan with Buddhist monks who had studied in China. According to the Japan Tourism Agency's account at Kōzan-ji, the Zen priest Eisai (1141-1215) came back from China with tea seeds and gave some to the monk Myōe, who planted them near the temple outside Kyoto about 800 years ago. Tea helped monks stay awake through long meditation. Myōe's planting led in time to large-scale cultivation at Uji, about 30 km to the south-east, still one of Japan's leading tea districts; Uji growers bring the first tea of the year to Kōzan-ji every 8 November.

Japan kept the powdered, whisked tea that China gave up under the Ming. Powdered green tea, matcha, is at the centre of chanoyu, the Japanese tea ceremony. The Metropolitan Museum of Art dates the ceremony as it is known today to the sixteenth century, when tea masters such as Sen no Rikyū (1522-1591) turned from prized Chinese wares to rustic, austere utensils, the aesthetic called wabi.

Portuguese and Dutch traders brought the first tea to Europe in the very early 1600s, and it had reached Britain by the 1660s. The English East India Company at first bought tea in secondary markets and, by the early 1700s, directly from China. Volumes grew fast. MIT's history of the Canton trade gives China's tea exports as 92,000 pounds in 1700 and 2.7 million pounds in 1751. By 1800 the Company was buying 23 million pounds a year, and 27 million pounds in 1810.

In Britain tea was taxed so heavily that much of it was smuggled. The Commutation Act of 1784 cut the duty from 119 % to 12.5 % and, according to Royal Museums Greenwich, effectively ended the smuggling trade. The Company's monopoly ended in 1834. In the age of the clippers, ships raced home with the new season's crop; the Cutty Sark, launched in 1869 as a tea clipper, could carry about 10,000 chests. The Suez Canal opened the same year and soon gave steamships the advantage.

China wanted little that Europe made. Until the middle of the eighteenth century about 90 % of what British traders brought to Canton was silver. The answer they found was opium grown in Bengal, which came under British control in 1757. The Company was not allowed to ship opium to China itself, so private traders carried it and took silver in return. In 1828 their opium imports were worth 11.2 million dollars, 72 % of their trade. Shipments rose from about 1,000 chests in 1773 to 18,000 in 1828 and 40,000 in 1839.

In March 1839 the imperial commissioner Lin Zexu arrived in Canton with orders to end the trade. War followed. Britain won the First Opium War (1839-1842) and the Second (1856-1860). China ceded Hong Kong and opened five ports to foreign trade, and opium imports kept rising until they peaked at about 81,000 chests in 1884. The cup of tea on a British table was tied, through silver and opium, to one of the most damaging trades of the century.

Britain set out to grow its own tea. China-type tea was brought into India in 1836, and Indian plantations are less than 200 years old. After the Treaty of Yandaboo (1826) brought Assam under British rule, the Assam Company and later firms received forest land on cheap terms. Local people would not work for the low wages offered, so planters recruited migrants from other parts of India under contracts enforced by criminal law. The Workmen's Breach of Contract Act of 1859 was applied to Assam's tea gardens from 1864, and an Act of 1865 let planters arrest workers who left without a warrant, a power that lasted until 1908. Death rates were severe: more than 5,500 of about 90,000 labourers died in 1863-1866, according to figures cited by the historians Ajanta Sharma and Khwairakpam Premjit Singh, and 7,614 immigrant labourers died in the province in 1884. The penal law of 1859 was not revoked in Assam until 21 April 1926.

Ceylon (Sri Lanka) came to tea through disaster. Coffee leaf rust wiped out its coffee estates (see the history of coffee), and the Sri Lanka Tea Board describes the early 1880s as the time the coffee economy collapsed. A Scottish planter, James Taylor, had already withered his first tea leaves on the Loolecondera estate, where the Kandy and Dimbula districts meet, in 1867. By the time the blight struck he had nineteen acres under tea and had shipped a first small consignment, 23 lb in all, to England. More than 120,000 hectares of coffee land then had to be cleared and replanted with tea.

World tea production reached 6.7 million tonnes in 2022, according to FAO's Intergovernmental Group on Tea. China grew 3.34 million tonnes, nearly half the total, much of it green tea for its own market. India followed with 1.37 million tonnes, 20.5 %. Kenya (542,561 t) and Sri Lanka (255,973 t) are the largest exporters of black tea; Sri Lanka's crop fell by 15.6 % in 2022 after a ban on chemical fertiliser in 2021 and an economic crisis. FAO notes that tea supports millions of smallholder farmers in low-income countries, and that climate change, volatile prices and falling returns threaten them.