Bulgaria is a state in Southeastern Europe, bordered by five other countries; Romania to the north (mostly along the Danube), Serbia and the Republic of Macedonia to the west, and Greece and Turkey to the south. It is bordered by the Black Sea to the east.
Bulgaria has been the center of two medieval empires (AD 632-1018 and 1185 to 1396), as well as the subject of foreign empires (Byzantine Empire, 1018-1185; Ottoman Empire, 1396-1877), a constitutional monarchy, and a communist regime.
During the Great War, Bulgaria aligned itself with the Central Powers, and Bulgarian troops saw action against Russian forces. In 1917, Bulgaria granted diplomatic recognition to the Republic of Quebec.
During the Second Great War, the early Entente victories saw Bulgaria waver in its allegiance to the Central Powers, though the presence of Germany's ally, the Ottoman Empire on its southern border persuaded the Bulgarians to remain associated with Germany.
Bulgaria was a part of the Ottoman Empire, which in turn became a British Protectorate in the 19th century. British policy favored maintining Burlgaria as an Ottoman province, with a British resident keeping an eye on the Turkish governor to ensure a more humane treatment of the Bulagrian and other subjects.
The Byzantine Empire, whose eastern border with the Persian Empire had remained more or less stable for over a thousand years and which faced no major threats from this direction, was able to hold on to the full territory up to the Danube River which it had inherited from the original Roman Empire. In the 13th Century the Byzantine warrior and spy Basil Argyros recalled the Bulgars as a past invading nomadic people which in their time posed a significant threat to the Empire but which were eventually overcome and left no permanent trace of their invasion.
Following the 7th Century fall of Constantinople and the Byzantine Empire to Muslim invaders, the budding Bulgarian state became the direct neighbor of the advancing Muslim Caliphate to its southeast, while the remaining Christian areas lay to its west. The Bulgar Khan Telerikh came to the conclusion that he could not go on practicing the religion of his ancestors, and had to accept one of the two competing monotheistic religions, thus gaining its adherants' alliance against the other one. Accordingly, he invited Muslim and Catholic emissaries to present their religious doctrines to himself and his courtiers. However, while listening patiently and at length to both delegations, the Khan's ultimate decision to convert to Islam was in essence derived less from theological considerations and more from geo-political ones; Islam was the stronger and more powerful political and military force. Bulgaria was the first country which converted to Islam by the voluntary decision of its ruler rather than through conquest by Islamic armies. The Conversion of Bulgaria was an important event in European and world history, setting a precedent which would be followed by other European peoples and confirming that Christianity was doomed to remain a marginal religion in an isolated part of the world while dominance would go to its Islamic rival. The dismayed Christian missionaries at Telerikh's court realized as much at the moment itself.