I am still hoping we get Bulgaria for a science civ (if Korea can be scientific, so can Bulgaria);
Not quite?
Korea's been scientific twice, but both times the leader was also a person who pushed for research and scientific development: Seondeok with her Cheomseongdae , Sejong wth the Jade Halls and the Hangul Alphabet. The basis for a scientific Korea was there, both times.
Bulgaria however? Makes no bloody sense as a scientific civ.
Firstly, Bulgaria lacks a good scientific leader. The Bolgar leaders were a bare step above steppe nomads. Of the tzars, Boris I and Simeon the Great had the council of Preslav, but this council was more of religious and cultural institution. The Glagotic and Cyrillic alphabets were designed with the purpose to spread religious texts and messages - not previously lost and recently recovered Hellenistic knowledge.
Secondly, you may be tempted to think otherwise because of the Macedonian Renaissance, as the territory currently belonging to the Republic of North Macedonia (whose culture and language is strongly linked to Bulgaria's), but the scholars of the Macedonian renaissance hailed from Macedon, which was part of the Byzantine empire. Contemporary Macedonia and ancient Macedon aren't the same entity, as the Greeks will fiercely remind you each time you mix the two up. The Macedonian Renaissance makes sense as a Byzantine ability, who could be scientific, but not a Bulgarian one.
Thirdly, tying in with the first point, look at the legacy of the First Bulgarian Empire. The achievements of Boris I and Simeon the Great (which also coincided with a period of Byzantine weakness, hence why the Bulgarian empire became the most powerful Kingdom in eastern Europe for about a century - they simply filled the power vacuum) were largely cultural and religous - Eastern Orthodoxy spread around the slavic world like wildfire, especially the Balkans. Cultural traditions such a the Cyrillic alphabet and polyphonic singing were introduced, and are still practised to this day. Many of the monasteries and castles build during these periods have since become tourist attractions. Nationalistic sentiment is embedded into the population from a young age, and everyone is well-read upon the cultural traditions and history of their nation. Domestic tourism is massive in Bulgaria and keeps the economy somewhat afloat, in spite of the dwindling population.
The point I'm trying to make here is that science makes no sense for Bulgaria, not moreso than it does for the Cree or the Zulu. Other than the cyrillic alphabet, Bulgaria's scientific achievements are insignificant. Their culture however? Rich, deep, layered and relevant to the present day. They make a perfect case for a warmongering civ with a strong cultural (or religious, or both) bonus.
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As far a scientific civs go, I think it depends on the timeline, does it not? Scientific advancement isn't a constant thing - China was highly advanced during the classical and medieval eras, but by the Industrial era were utterly backwards compared to their contemporaries. Japan was scientifically weak until the industrial era and now are amongst the most well-educated and creative nations in the world. Most nations can take the scientific role - but only a few (Greece, Rome/Byzantium, Assyria/Babylon, Persia) have fit the bill consistently enough to really warrant a scientific CUA. For the rest, it really depends on the chosen leader and which time period he or she thrust the entire nation in.