Technically, tea is any drink brewed from the leaves of the Camellia sinensis plant. In the US, we commonly refer to all plant and herb-infused drinks as "tea". If you like being technical, then you would only refer to drinks brewed with the Camellia sinensis plant as "tea". Herbal and plant-brewed beverages are technically called "tisanes". All that being said, we're cool calling them tea ... while acknowledging there's a difference between Camellia sinensis and non-Camellia sinensis-based beverages ;)
Practically, the question "where does tea come from?" is answered by taking a look at where the Camellia sinensis plant is grown, historically and today. Random fact: in Chinese, Camellia sinensis translates to "tea flower" or “tea tree”. While the Camellia sinensis plant originated in China, it abundantly grows today in China, India, Kenya, Sri Lanka, Turkey, Indonesia, Vietnam, Japan, Taiwan, Iran, Argentina, and Hawaii (US). Camellia sinensis is mainly cultivated in tropical and subtropical climates, in areas with at least 50 inches of rainfall per year. Tea plants prefer a rich and moist growing location in full to partial sun. Many high quality teas are grown at high elevations, up to 4,900 feet, as the plants grow more slowly and acquire more complex flavors. Two principal varieties of Camellia sinensis are used; the small-leafed Chinese variety (C. sinensis sinensis) used for most tea types, and the large-leafed variety native to the Assam region of India (C. sinensis assamica), used mainly for black tea. Other cultivars and hybrids of these two main varieties exist today, each with different flavor characteristics. The type of plant, along with the terroir in which it is grown, and how the leaf is processed, all culminate to produce different tea types.
Photo Credit: Rishi Tea