Bulgaria–Turkey border
The Bulgaria–Turkey border (Bulgarian: Българо-турска граница, romanized: Būlgaro-turska granitsa,Turkish: Bulgaristan–Türkiye sınırı) is a 259 km (161 mi) long international border between the Republic of Bulgaria and the Republic of Turkey. It was established by the Treaty of San Stefano in 1878 as an inner border within the Ottoman Empire between Adrianople Vilayet and the autonomous province of Eastern Rumelia.