This is the well known Miyak bayrak. It's a kind of Macedonian flag, used since ancient times. It was forbiden when the Ottomans conquered Macedonia, so the only ones who steel kept using it were the Miyaks(Western Macedonians) becouse they were living in very high-mountanous regions.
There are two of this flags that survived untill modern days, originating from Kostur/Kastoria. In the city-sphere of Kostur, was in use untill the middle 19century, when it was officialy forbiden from the Ottomans, under FANARIOTE pressure. (ИСАЙЯ МАЖОВСКИ "Възпоминания", София, 1922 г., 19/20 стр.)
The Miyak, Isaia Mazhovski (1852-1922) writes that this flag was in use in Macedonia, since the split of Alexander Empire into the hands of his dukes.(ИСАЙЯ МАЖОВСКИ "Възпоминания", София, 1922 г., 19/20 стр.)
About the flag.
Central symbol - We all know it well, the symbol of Maco's since ancient times.
The Cross - Meaning Jesus Christ the victor.
The Two-headed Eagle. Representing the spiritual unity of the world, the world ruling Macedonian empire. Is it true that Alexander and his descendants ruled out both Europe and Asia.
The Lion - Symbol of Macedonian strenght and victory
The Dragon - Symbol of the Celts/Gauls, who were invading Macedonia hundreds of times.
The Moon and star - Symbol of the Bogomils, who flourished in Macedonia.
Isaia Mazhovski, also speaks about a song originating since the time of the Macedonian empire after Alexander's death, when his dukes ruled.
“Застоjaл ми се воjвода,
Над големи град Солуна,
До него стоjaт два брата,
Два брата, два баjрактара
Високо баjрак држеје.
Тихиoт ветeр вееше,
Широко знаме ширеше,
Широка сенка држеше.
Све Солун града покрило,
И солунските чаршии,
В чаршии има седлари
И е млади златари,
Седлари седла правеjе,
Златари јузди лееје,
За тиа силни ајгри,
На македонските војводи.
ИСАЙЯ МАЖОВСКИ „Възпоминания”, София, 1922 г., 20 стр.