There is a story, it might be myth or it might be true, about the origin of Mandheling coffee. It explains why if you are ever in Sumatra looking for these coffee fields on a map, you may never find them, because Mandheling is an ethnic group (similar to Batak), not a town.
The story goes that during the Japanese occupation a soldier asked a shop owner what the excellent coffee was that he was being served. Misunderstanding the question and thinking he was being asked what HE was, the owner's reply was "Mandheling". After the war the soldier contacted a broker in Sumatra asking if the excellent coffee "Mandheling" was commercially available, and they shipped 15 tons of coffee to Japan that year. The rest, as they say, is history.
Of course Sumatra did not start producing coffee just because of this encounter. Coffee production began there in the 18th century under colonial domination in the northern region of Aceh before spreading to Lake Toba, Lintong, Nihuta, Sumbul and Takengon. The Mandheling are the Indonesian ethic group that is most involved in coffee production.
Over time Mandheling has gained a reputation for its consistent quality and its very specific cup qualities which include a desirable deep husky flavour.