https://en.wikipedia.org/wiki/History_of_the_Balkans
Around 513 BC, as part of the military incursions ordered by Darius I, a huge Achaemenid army invaded the Balkans and tried to defeat the Western Scythians roaming to the north of the Danube river. Several Thracian peoples, and nearly all of the other European regions bordering the Black Sea (including parts of the modern-day Bulgaria, Romania, Ukraine, and Russia), were …