The flag, a tricolor of horizontal stripes (from top: white, green, red), while a visible national emblem, is not so vested with specific meaning.Among the most potent symbols of Bulgarian national identity are several key historical events: the founding of the Bulgarian states in 6; the partition of Bulgaria in the Treaty of Berlin (1878); the union with Eastern Rumelia (an autonomous Ottoman province created by the partition) in 1885; the successful defense against Serbian encroachment in 1885; and territorial gains, losses, and humiliation in the Balkan wars (1912–1913) and World War I (1914–1918).It is bordered on the east by the Black Sea, on the north by Romania and the Danube River, on the south by Greece and Turkey, and on the west by Macedonia and Serbia.The landscape consists of mountains, foothills, and plains.The population increased gradually for most of the twentieth century, but has decreased by more than 700,000 people since 1988.This decline stems from out-migration and falling birthrates during the uncertain postsocialist period.
Many Gypsies also speak Turkish, and some speak Romanian.
Smaller groups include Russians, Armenians, Vlachs, Karakachans, Greeks, Tatars, and Jews.
The 1992 census did not include a category for Pomaks (Bulgarian Muslims), who are often identified as one of Bulgaria's four main ethnic groups and constitute an estimated 3 percent of the population.
, Slavs began to settle the Thracian-occupied eastern Danubian plains.
In the seventh century, they joined with invading Bulgars to gain control of a sizable territory, which they defended against Byzantium in 681, gaining recognition as the first Bulgarian state.