Not original commenter (and long read in the source) but:

“In the 1920s, in order to save money on importing coca leaf from South America, Japan’s pharmaceutical companies determined to set up coca plantations in Taiwan, Iwo Jima, and Okinawa, and also purchased from Dutch growers in Java, who had been cultivating coca there since the 1850s (Karch 1999, 147, 156).

Company and Taiwan Shoyaku companies, on a combined 694 acres of land in the Taiwanese interior, produced a total of 700,814 kilograms of coca leaf between 1927 and 1931, about one- fifth of which was transferred to Japan for processing; the rest was processed into crude cocaine by those companies’ factories in Taiwan.18 Karch calculates the total production of coca leaf in Taiwan during these years at around 150,000 tons per year, which, once processed into cocaine, would have yielded around seven tons per year (1999, 155–156).”

Source

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My information comes from "Cocaine - An Unauthorized Biography" by Dominic Streatfield - basically covers the entire history of coca and cocaine from the time of the Incas to the coke epidemic of the 1980s. A great read.