Most words for ‘tea’ around the world are ultimately of Chinese origin, but they differ in their form due to their dissemination via different routes. The differences begin on Chinese soil: most Sinitic languages have a form similar to the Mandarin chá, but Min Nan (alternatively, Fujianese, Hokkien, or Taiwanese) Chinese has instead forms like te (pronounced with a high tone in Taiwanese).
The Dutch traders from the Dutch East India Company, who were the early main importers of tea into Europe, happened to have their main contacts in Amoy (Xiamen) in Fujian; as a result, they adopted the word thee, which they subsequently spread over large parts of Europe, as can be seen from the enlarged portion of the above map.
The only two languages in Western Europe to have chai-based words for ‘tea’ are Basque and Portuguese (more on the latter below). The same Min Nan influence is visible in the word forms found in languages spoken in the former Dutch colonies, such as Indonesian teh, Sundanese entèh, Javanese tèh, etc.
The Dutch were responsible for first introducing tea to England in 1644, but by the 19th century most British tea was purchased directly from merchants in Canton, where the form cha was used. Still, the British never replaced their Dutch-derived word for ‘tea’. In Standard English, the vowel changed from /e:/ to /i:/ as part of the general change, known as the Great Vowel Shift (some dialects, which did not undergo the complete GVS, preserve the old form tay). This pronunciation is reflected in many languages that took over the word from English, such as Yoruba (spoken in southwestern Nigeria) tii, !Xóõ (Botswana) tîi, Cocopa (California and northern Mexico) ti.
Though the Dutch were the dominant tea importers in the 1600s, they were not the first to bring the beverage to Europe. The Portuguese started trading in tea in the 16th century, and their trade route went via Macao rather than via Amoy. Consequently Portuguese uses chá, derived from Cantonese cha. The Korean and Japanese words come from Mandarin, which also used a “cha” form,, though they retain older pronunciation, allowing us not only to trace but also to date the borrowing. Tea—both the drink and the label—also traveled overland, speading in such a manner from China to Eastern Europe and Central Asia. Persia, a crucial node in trans-Eurasian trade, bequeathed the Persian grammatical suffix –yi, which shows up in the Arabic shāy, Turkish çay, and Uzbek choy. Hence also the Russian chaj, as well as the similar words found in the Finno-Ugric and Turkic languages of Central Volga and Central Asia.
Such patterns of trade and linguistic borrowing also explain why related languages often have differing words for ‘tea’: for example, Finnish and Estonian both use te-based forms, while Mordvin, Mari, and Udmurt all have chai-based forms. Yet, in Eastern Finland and in Helsinki forms reminiscent of—and borrowed from—the Russian chaj are often used for black tea but never for green tea, reflecting perhaps Russians’ tea-drinking preferences. The overland trade in tea also accounts for the chai-based words in most languages of the Caucasus, with the exception of Armenian.
World Atlas of Language Structures edited by Dryer, Matthew S. & Haspelmath, Martin