Flag of Bulgaria

In 866, Pope Nicholas I advised Prince Boris who had recently Christianised his people to switch from the practice of using a horse tail as a banner to adopting the Holy Cross.[2]

Later illuminated versions of the chronicles of John Skylitzes and Constantine Manasses depict the army of Khan Krum carrying flags either in monotone red,[3] or red with a black border.[4] The army of Simeon the Great is also depicted carrying red banners of varying shape.[4] The Radziwiłł Chronicle also depicts Tzar Simeon I's army under a red flag in the 921-922 campaign against Byzantium, but the depiction of the Hungarian invasion of 894 featured the Bulgarian fortress of Drastar under a white flag with a crescent and a six-pointed star. Any pictorial representations of flags in the manuscripts mentioned above, regardless of the faction or time depicted, conform strongly to the overall illustration style used in each manuscript. In addition, none of those manuscripts dates to the time of the First Bulgarian Empire. The historicity of those flags is thus impossible to verify.

Depictions of Bulgarian flags can be seen on various portolan maps from the 14th and 15th centuries. On those maps, the flags commonly have a white or golden[5][6] background and depict either the insignia of the ruling House of Shishman,[7] or unknown symbols[8][9] in red. Those drawings are markedly more diverse than the flags of the neighboring countries such as the Eastern Roman Empire, the Golden Horde or the Serbian Empire, which in the same maps are largely consistent.

After the liberation of Bulgaria following the Russo-Turkish War in 1878, the flag was described in the Tarnovo Constitution of 1879 as follows:

Art. 23. The Bulgarian people's flag is three-coloured and consists of white, green and red colours, placed horizontally.[10]

From 1947-1990 the emblem of the People's Republic of Bulgaria was placed on the left side of the white stripe. It contained a lion within a wreath of wheat ears below a red star and above a ribbon bearing the date 9 September 1944, the day of Bulgarian coup d'état of 1944 which led to the establishment of the People's Republic of Bulgaria. In 1971, it was changed so the ribbon bearing the years 681, the year of the establishment of the First Bulgarian Empire by Asparukh and 1944.

After the fall of Communism in 1990, the then-enforced Zhivkov Constitution was amended so the flag could be reverted to the pre-Communist era.[11] The new Constitution of Bulgaria, adopted in 1991, describes the Bulgarian flag as follows:

Art. 166. The flag of the Republic of Bulgaria shall be a tricolour: white, green and red from top, placed horizontally.[12]

A popular version of the flag, which has no official status, is also commonly known. It has the full coat of arms on the left of the flag, placed across the white and green fields only.[13]