Bulgaria issued one miniature sheet in 2018 that 1300 years ago Khan Tervel (675-721) https://en.wikipedia.org/wiki/Tervel_of_Bulgaria made his victory over the Arab Army.
In the border of the sheet is depict a medieval type vessel, at that time the Byzantine navy used mostly “dromon” as warship, and the vessel depict is a dromon.
The “dromon” ruled over the eastern Mediterranean until the fall of Constantinople and was the most famous warship of the Byzantine navy. It was a large fast galley in general a birime of the fleet of the Eastern Roman Empire from 800 to 1300 AD.
Two of three rowers by oar, and was propelled by 80 oars, rowed by up to 240 rowers, and carried 80 soldiers.
The largest had dimensions of length 70 metres, beam 7 metres.
Source Internet.
Bulgaria 2018 2.00L sgMS?, scott?
Bulgaria 2019 0.65 l sg?, scott?