معاهدة سان ستيفانو
The issue of irredentism and nationalism gained greater prominence after the Treaty of San Stefano. It established a Principality of Bulgaria, with territory including most of Moesia - the plain between the Danube and the Balkan mountains range (Stara Planina), the regions of Sofia, Pirot, and Vranje in the Morava Valley, Thrace - Northern Thrace, parts of Eastern Thrace, and nearly all of Macedonia. This treaty laid grounds for much of the later claims for a Greater Bulgaria. However, the Treaty of San Stefano was a preliminary one and the borders of the newly created Bulgaria were established in the Treaty of Berlin. It saw the previous territory divided in three – the Principality of Bulgaria, the autonomous province of Eastern Rumelia, and Macedonia, which remained under Ottoman control.