It’s unclear when coffee planting arrived in Sumatra specifically. Java was the coffee king of Indonesia (aka the Dutch East Indies) for at least 100 years after cuttings first arrived from Ceylon before coffee of any significant volume was grown on other islands. And well into the 20th century, much of coffee grown throughout Indonesia was called Java. As with Ceylon, rust disease decimated coffee crops throughout Indonesia at the end of the 19th century. Unlike it’s coffee mother ship, Indonesia did not switch to growing mostly tea.