Bulgaria i/bʌlˈɡɛəriə/ (Bulgarian: България, Balgariya, IPA: [bɤ̞ɫˈɡarijɐ]), officially the Republic of Bulgaria (Република България, transliterated: Republika Balgariya, IPA: [rɛˈpublikɐ bɤ̞ɫˈɡarijɐ]), is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east. With a territory of 110,994 square kilometers (42,855 sq mi), it ranks as the 15th-largest country in Europe.
Prehistoric cultures began living on Bulgarian lands starting in the Neolithic period. Its ancient history has been marked by the presence of various civilizations. The emergence of a unified Bulgarian ethnicity and state date back to the 7th century AD. Subsequent political entities that emerged preserved the traditions of the First Bulgarian Empire, at times covering most of the Balkans, becoming a cultural hub for Slavic peoples in the Middle Ages. With the downfall of the Second Bulgarian Empire in 1396, its territories came under Ottoman rule for nearly five hundred years. The Russo-Turkish War of 1877–1878 resulted in the third Bulgarian state, recognized in 1908. Shortly afterwards, Bulgaria had a series of major conflicts with its neighbours and allied with Germany for both World Wars. After World War II it became a people's republic and was a part of the Warsaw Pact until 1989, when the Communist Party allowed multi-party elections. At this time Bulgaria transitioned to democracy and free market capitalism was introduced. Bulgaria is a member of the European Union, NATO, the Council of Europe, a founding state of the OSCE, and has taken a seat in the UN Security Council three times.
Bulgaria's population of 7.36 million people is predominantly urban and is concentrated mainly in the administrative centers of its 28 provinces. With 1.2 million people Sofia is the largest city, where most economic and political activities are concentrated. The economy relies on local natural resources with the strongest sectors being heavy industry and agriculture. Bulgaria is home to some of the most ancient cultural artifacts in the world and is a historical crossroad of various civilizations.