Treaty of Neuilly-sur-Seine
In Antiquity, the Jireček Line divided Latin (in the north) and Ancient Greek (in the south) language influence in the Balkans, with Northern Bulgaria to the north of it and Southern Bulgaria to the south. Much later, after the Liberation of Bulgaria in 1878, all of Northern Bulgaria and the region of Sofia became the Principality of Bulgaria while most of the rest of Southern Bulgaria was part of Eastern Rumelia until the Bulgarian unification in 1885. Pirin Macedonia became part of Bulgaria after the Treaty of Bucharest of 1913, and the only Bulgarian gains by the otherwise catastrophic post-World War I Treaty of Neuilly-sur-Seine of 1919 were two small strips of land in southern Sakar.