The name of Heinrich Kiepert is closely linked to the Congress of Berlin (1878) during which his "Ethnographic Outline of Eastern Europe" (1876) enjoyed an unquestioned authority and was the standard reference, even for Chancellor Bismarck. However, at the request of the Greek historian Constantinos Paparrigopoulos, the German geographer produced a new map, in 1878 before the Congress, called "ethnocratic." So what were the new ethnographic results? What were the modifications that Kiepert’s map underwent in reference to the territorial borders between the sovereign States in the Balkans? Did the new Paparrigopoulos-Kiepert map have any influence on the decisions contained in the Treaty of Berlin? These are some of the matters this article attempts to deal with based on the unpublished correspondence of Kiepert and Paparrigopoulos in which they discuss the cartography and ethnography of the Balkans. Their debate, even today, has lost none of its relevance.