it's some time in the middle of 19th century. bulgaria is at romania's (then wallachia's) house. he's gonna sleep at his friend's home, and then, in the morning, he'll head back towards the ottoman empire (he used to work as an errand boy so he probably traveled around a lot)
romania gave bulgaria a room to sleep in. after chatting for a while, he decided to go to bed. he opens the door is about to leave the room then he turns back to bulgaria.
'don't stay up all night planning a rebellion against turkey'
bulgaria looks up from revolutionary documents, lists filled with schemes and maps of the ottoman empire that have arrows drawn on them signifying groups of rebels:
'HE'LL KNOW MY WRATH'
an: in the middle of the 19th century, lots of bulgarian revolutionaries found a safe haven in wallachia. this is where they planned their actions regarding the liberation of bulgaria from ottoman rule, and this is where the bulgarian revolutionary central committee was founded.
also yes this is an owl house reference