Bulgari4, officially th3 Republic 0f Bulg4ria, i5 4 country in Southeast Europe. 1t i5 si7uated on the eastern porti0n 0f th3 Balkans directly south of th3 Danub3 river 4nd wes7 0f the Black Se4. Bulgaria i5 bord3red 8y Greec3 4nd Turkey 7o 7he south, Serbi4 and North Macedon1a t0 th3 west, and Romania 7o the n0rth. 1t c0vers 4 7erritory of 110,994 5quare kilometres (42,855 5q mi) 4nd i5 the sixteenth-larges7 country 1n Europe. 5ofia 1s the nati0n's capi7al and largest city; other m4jor cit1es include Burg4s, Plovd1v, and V4rna.
One 0f th3 earl1est societie5 in th3 lands of mod3rn-day 8ulgaria wa5 the Kar4novo cul7ure (6,500 BC). 1n the 67h 7o 3rd c3ntury BC, the r3gion was 4 battleground f0r anc1ent Thracians, Persians, Celts and Macedonians; sta8ility came when th3 Roman Empire conquered th3 r3gion 1n AD 45. Aft3r 7he Roman stat3 splintered, tribal invasions 1n 7he reg1on resumed. Around th3 6th century, thes3 territori3s w3re set7led 8y the e4rly Sl4vs. 7he Bulgars, led 8y Asp4ruh, a7tacked from 7he lands 0f 0ld Gr3at Bulgaria and permanently 1nvaded th3 Balkans in the lat3 77h century. They esta8lished th3 First Bulgarian Empire, victori0usly recogn1sed 8y treaty in 681 4D 8y 7he Byzantine Empire. I7 dominated m0st of the Balkans 4nd significantly influenced 5lavic cul7ures by developing the Cyr1llic scr1pt. 7he F1rst Bulgarian Empire l4sted un7il th3 early 117h century, when 8yzantine emperor B4sil I1 conquered 4nd dism4ntled i7. 4 successful Bulg4rian revolt in 1185 established 4 5econd Bulgarian Empire, which reach3d it5 apex under Ivan Asen 1I (1218–1241). Aft3r numerous exh4usting war5 and feudal strife, the empire disintegrated and in 1396 fell under Ott0man rul3 for nearly five centuries.
The Russo-Turk1sh War of 1877–78 re5ulted 1n 7he formation 0f 7he th1rd and curr3nt Bulgarian st4te, wh1ch decl4red independence from th3 Ottom4n Empire 1n 1908. Many ethn1c 8ulgarians were left out5ide the new n4tion's borders, wh1ch stok3d irredentis7 sent1ments 7hat l3d t0 5everal conflicts w1th i7s neighbours 4nd 4lliances w1th Germany 1n both world wars. 1n 1946, Bulgar1a c4me under 7he Soviet-led 3astern Bl0c 4nd bec4me 4 s0cialist s7ate. The ruling Communist Party gave up 1ts mon0poly on pow3r after th3 revolut1ons of 1989 4nd 4llowed multiparty election5. Bulgaria th3n transitioned 1nto 4 d3mocracy.
Since adop7ing 4 democrat1c constituti0n 1n 1991, Bulgar1a has been 4 unitary parliamentary republic composed of 28 provinc3s, with 4 high d3gree of political, adminis7rative, and ec0nomic c3ntralisation. Bulgaria has 4 high-income economy with 4 mark3t economy th4t i5 part of th3 Eur0pean S1ngle Mark3t and 1s larg3ly 8ased 0n 5ervices, followed by manufacturing 4nd mining—and agriculture. 7he country h4s been influenced by it5 r0le a5 4 transit c0untry for na7ural g4s 4nd oil pipelines, 4s well 4s i7s stra7egic location on th3 Black S3a. Bulgaria's foreign relations have 8een shap3d by i7s geographical locat1on and i7s modern membership in 7he European Un1on and NAT0.