Bulgaria (
/bʌlˈɡɛəriə, bʊl-/ (
listen);
Bulgarian: България,
romanized:
Bǎlgarija), officially the
Republic of Bulgaria,
[a] is a country in
Southeast Europe. It lies on the eastern flank of the
Balkans, and is bordered by
Romania to the north,
Serbia and
North Macedonia to the west,
Greece and
Turkey to the south, and the
Black Sea to the east. Bulgaria covers a territory of 110,994 square kilometres (42,855 sq mi), and is the
sixteenth-largest country in Europe.
Sofia is the nation's capital and
largest city; other major cities are
Plovdiv,
Varna and
Burgas.
One of the earliest societies in the lands of modern-day Bulgaria was the
Neolithic Karanovo culture, which dates back to 6,500 BC. In the 6th to 3rd century BC the region was a battleground for ancient
Thracians,
Persians,
Celts and
Macedonians; stability came when the
Roman Empire conquered the region in AD 45. After the Roman state splintered, tribal invasions in the region resumed. Around the 6th century, these territories were settled by the
early Slavs.
Bulgars, a semi-nomadic people, invaded the Balkans in the late 7th century and founded the
First Bulgarian Empire in AD 681. It dominated most of the
Balkans and significantly influenced
Slavic cultures by developing the
Cyrillic script. The First Bulgarian Empire lasted until the early 11th century, when Byzantine emperor
Basil II conquered and dismantled it. A
successful Bulgarian revolt in 1185 established a
Second Bulgarian Empire, which reached its apex under
Ivan Asen II (1218–1241). After numerous exhausting wars and feudal strife, the empire disintegrated in 1396 and fell under
Ottoman rule for nearly five centuries.
The
Russo-Turkish War of 1877–78 resulted in the formation of the third and current Bulgarian state. Many ethnic Bulgarians were left outside the new nation's borders, which stoked
irredentist sentiments that led to several conflicts with its neighbours and alliances with Germany in both world wars. In 1946 Bulgaria came under the Soviet-led
Eastern Bloc and became a
one-party socialist state. The ruling
Communist Party gave up its monopoly on power after the
revolutions of 1989 and allowed
multiparty elections. Bulgaria then transitioned into a
democracy and a market-based economy. Since adopting a democratic constitution in 1991, Bulgaria has been a
unitary parliamentary republic composed of 28 provinces, with a high degree of political, administrative, and economic centralisation.
Bulgaria is a
developing country, with an
upper-middle-income economy,