Diasporas
Historically, there have been sizable Greek and Bulgarian communities in the territories which form present day Bulgaria and Greece respectively. These communities today are mostly non-existent due to the population exchanges between Greece and Bulgaria which were directed under the Treaty of Neuilly in 1919.
According to the 2001 census, there were 35,104 Bulgarian citizens in Greece, constituting 4,7% of all foreigners in Greece. However, that number has risen since then, as in 2003-2004, Bulgarians accounted for 9,8% of residence permit holders in Greece, out of which 473 were students and 2,059 were married to EU nationals. In the academic year 2002-2003, there were 2,873 non-ethnic Greek citizens of Bulgaria in Greek state schools. There are numerous publications in Greece for the Bulgarian community, including the bilingual newspaper България днес/Βουλγαρία σήμερα (Bulgaria today).
According to the 2001 census, there were 3,408 Greeks in Bulgaria. This figure most likely includes, former political refugees, remnants of the population exchanges, students, and businessmen and their families. In addition, there were 4,108 Sarakatsani
Read more about this topic: Greco-Bulgarian Relations