Greater Albania is an irredentist concept of lands that are considered to form the national homeland by many Albanians, based on claims on the present-day or historical presence of Albanian populations in those areas. In addition to the existing Republic of Albania, the term incorporates claims to regions in the neighbouring states, the areas include Kosovo and the Preševo Valley of Serbia, territories in southern Montenegro, northwestern Greece (the Greek regional units of Thesprotia and Preveza, referred by Albanians as Chameria, and other territories that were part of the Vilayet of Yanina during the Ottoman Empire), and a part of western Republic of Macedonia.
The unification of an even larger area into a unique territory under Albanian authority had been theoretically conceived by the League of Prizren, an organization of the 19th century whose goal was to unify the Albanian inhabited lands (and other regions, mostly from the region of Macedonia, Epirus and Montenegro) into a single autonomous Albanian Vilayet within the Ottoman Empire. However, the concept of a Greater Albania, as in greater than Albania within its 1913 borders, was implemented only under the Italian and Nazi German occupation of the Balkans during World War II. The idea of unification, has roots in the events of the Treaty of London in 1913, when roughly half of the predominantly Albanian territories and 40% of the population were left outside the new country's borders, something that Albanians have tended to regard as an injustice imposed by the Great Powers.