The Bulgarian Democratic Republic (BDR; Bulgarian: Българска демократична република, БДР Bǎlgarska demokratična republika, BDR), informally known as Bulgaria (България Bǎlgariya), is a socialist republic in Southeast Europe, and one of 26 constituent republics of the Eurasian Union. Its capital and largest city is Sofia and its official language is Bulgarian. The republic is a one-party state governed by the Communist Party of Bulgaria, the national branch of the All-Union Communist Party, the founding and ruling political party of the Eurasian Union. Home to just over 7 million people, Bulgaria is the fifth-least populous union republic.

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