Here’s some known tea producing locations from the 14th century, from William Wayne Farris’ book on the history of Japanese tea.
The habit-forming beverage, now sweeter and tastier than ever, pros- pered within this decentralized context. Beginning around 1350, a bud- ding tea industry began to emerge. Different regions of Japan competed against each other with their own unique brands of tea:
Of the famous tea mountains of our dynasty, Toganoo is the best. Ninnaji, Daigoji, Uji, Hamuro [in Yamato], Hannyaji [in Yamato], and Kannōji [in Tanba]: these are next. In addition, Muroo in Yamato, Yashima in Iga, Kawai in Ise, Kiyomi in Suruga, and Kawagoe in Musashi—all these are specially mentioned throughout the realm. The famous places at Ninnaji and Yamato and Iga compare to the tea fields here and there just like agate to trash. Then, too, Toganoo compares to Ninnaji and Daigoji like gold to lead.61
This quotation, taken from a source completed during the mid-fourteenth century, lists the most famous tea production centers in Japan. While the most delicious tea apparently still came from Yamato and Yamashiro, it is notable that tea drinkers could also find the tasty beverage in Tanba, Iga, Ise, Suruga, and Musashi.
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These named places may have been the best, but tea patches were also located “here and there” throughout the realm. Other records dating to the period 1340–1400 describe fields in Saidaiji and Hamuro in Yamato, Yamashina (2), Uji (2), and Saga in Yamashiro, Kii (3), Settsu (3), Tanba (3), Izumi (2), Mino and Shimōsa (3).62 By the 1350s, tea was being cultivated, processed, and consumed widely throughout the Kinai, central Honshu, and the Kanto plain. As one writer of the 1300s put it, “new tea flows unexpectedly throughout the world.”63 Outstanding brand-name centers of tea had multiplied with the shift to a more regional political and eco- nomic structure, and would become an essential ingredient in the rise of a consumer society much later.
With many different brands competing against one another, tea was on its way to becoming big business, as is implied in this incident dated to the first half of the fourteenth century: