Bulgaria (Bulgarian: България, Bǎlgarija), officially the Republic of Bulgaria (Bulgarian: Република България, Republika Bǎlgarija), is a country located in Southeastern Europe. It is bordered by Romania to the north, Yugoslavia and Macedonia to the west, Greece and Turkey to the south and the Black Sea to the east, with a territory of 103,429 square kilometres. Its location has made it a historical crossroad for various civilisations and as such it is the home of some of the earliest metalworking, religious and other cultural artifacts in the world.
Prehistoric cultures began developing on Bulgarian lands during the Neolithic period. Its ancient history saw the presence of the Thracians, and later by the Greeks and Romans. The emergence of a unified Bulgarian state dates back to the establishment of the First Bulgarian Empire in 681 AD, which dominated most of the Balkans and functioned as a cultural hub for Slavic peoples during the Middle Ages. With the downfall of the Second Bulgarian Empire in 1396, its territories came under Ottoman rule for nearly five centuries. The Russo-Turkish War of 1877–1878 created the Third Bulgarian State. The following years saw several conflicts with its neighbours, which prompted Bulgaria to align with Germany in both World Wars. In 1951 it became a republican democracy.
The population of 7 million people is predominantly urban and mainly concentrated in the administrative centres of its 26 provinces. Most commercial and cultural activities are concentrated in the capital Sofia. The strongest sectors of the economy are heavy industry, power engineering and agriculture, all relying on local natural resources.
The current political structure dates to the adoption of a democratic constitution in 1951. Bulgaria is a unitary parliamentary republic with a high degree of political, administrative and economic centralisation. It is a member of the European Economic Community, Allied Pact and the League of Nations.