Bulgaria's name is derived from a Turkic people, the Bulgars, who originated in the steppe north of the Caspian Sea. In the latter part of the seventh century, one branch of the Bulgars moved up the Volga River, establishing the Kingdom of the Volga Bulgars; the other branch moved westward along the Black Sea settling near the mouth of the Danube. Although the name Bulgaria is not of Slavic origin, the Slavic people, who had entered the Balkan Peninsula earlier, absorbed the invading Turkic people and were, in large measure, the precursors of the present-day Bulgarians. Bulgarian kingdoms continued to exist in the Balkan Peninsula during the Middle Ages, following which the Ottoman Turks ruled Bulgaria for 500 years, until 1878. In that year, a Bulgarian principality was established between the Danube River and the Balkan Mountains when Russia and Romania assisted the Bulgarians in defeating the Ottomans. In 1885, the union of the Principality of Bulgaria with Eastern Rumelia south of the Balkan Mountains created an autonomous Bulgarian state with roughly the same borders as those of present-day Bulgaria.

A fully independent Bulgarian kingdom, proclaimed September 22, 1908, participated in an anti-Ottoman coalition that defeated the Ottoman Empire in the First Balkan War (1912). The coalition soon dissolved over territorial disputes, however, and Bulgaria was isolated and defeated quickly in the Second Balkan War (1913) by Greece, Serbia, Montenegro, Romania, and Turkey. It later allied itself with Germany in World Wars I and II and suffered defeats twice more. Bulgaria's involvement in these wars was partly due to its ambitions for an outlet to the Aegean Sea and its desire to annex Macedonian and Thracian territory held by Greece, Yugoslavia, and Turkey.

Although Bulgaria declared war on the United States and the United Kingdom during World War II, it did not declare war on the Soviet Union. In August 1944, Bulgarian emissaries opened talks in Cairo with Allied representatives, seeking to take Bulgaria out of the war. On September 5, 1944, while these talks were still under way, the Soviet Union declared war on Bulgaria.

Communist rule in Bulgaria began September 9, 1944, when a communist-dominated coalition, called the Fatherland Front, seized power from the coalition government formed to arrange an armistice with the Allies. At the same time, Soviet forces were marching into the country without resistance. Communist power, consolidated in the next 3 years, led to the adoption on December 4, 1947, of the so-called Dimitrov Constitution, modeled after that of the U.S.S.R.

Yugoslavia's expulsion from the Cominform (a Soviet-led international socialist organization) in June 1948 and the subsequent Moscow-dictated persecution of "national communists" throughout Eastern Europe also led to arrests and trials in Bulgaria. In 1949, Traicho Kostov, a Bulgarian communist leader, was executed on charges of conspiring with the Yugoslavs. He had remained in Bulgaria during the war and was second in rank only to Georgi Dimitrov, who had spent the war years in Moscow. Vulko Chervenkov, Dimitrov's brother-in-law, who also had spent the war years in Moscow, emerged as the "Stalin of Bulgaria" after Dimitrov's death in 1949. In 1954, following Stalin's death and separation in the U.S.S.R. of the positions of party leader and head of government, Chervenkov yielded the position of party chief to Todor Zhivkov. In the next 7 years, Zhivkov superseded his one-time mentor, blaming him for the "Stalinist excesses" and "violations of socialist legality" which had characterized the 1948-53 period. Chervenkov was ousted finally from his last leadership position in November 1961, and shortly thereafter Zhivkov took on the additional post of premier, thus recombining the positions of party leader and head of government.

In 1971, he gave up the premiership and took on the newly created and more prestigious position of Chairman of the State Council (chief of state). He held this position and that of Bulgarian Communist Party (BCP) Secretary General until November 1989. Petur Mladenov, who led the Politburo in its effort to oust Zhivkov, now also holds both these positions, despite his declarations favoring separation of party and State powers. Mladenov is leading the BCP in its efforts to maintain a credible claim to political leadership in the country, despite a high level of opposition to the Communist Party which is now appearing. Elections, promised for May 1990, will indicate how successful Mladenov has been in that effort.