The Sumatra bean goes through a sweating process and then the green is roasted to a perfect blonde or Vienna roast. Thus the Sumatran coffees are best from the Mandeling region. They are low in acid and topped with a syrup undertone hinting of chocolate.
Sumatra beans were lost for over 100 years, then found again to be cultivated in the Mandeling area. Of course, not all Sumatra coffees sweat, but we choose to buy the beans that go through that process. Years ago all coffee beans went through the sweating process simply because of the journey of travel shipping, thus taking on various diverse tastes – more than in their native regions and origins.