In which country is the capital called Sofia?

Explanation

Bulgaria is a country on the Balkan peninsula, bordering the Black Sea. The capital is called Sofia. Around 8 million people live in the country which covers an area of 110,910 km². The country was an important European state in the 9th and 10th century but later on lost its independence. It regained it in 1878. Bulgaria was communist from 1946 to 1990.