I feel the game is more madlibs than trying to represent any one period.
Like, especially for 800s, there's no frankish empire. Like, the frankish empire is the dominant force in the 9th and 10th century europe. You can't represent that period without a frankish empire equivalent.
The Calradian Empire feels more crisis of third century than later collapse, the Vlandians are just straight normans. The Sturgians are vaguely kieven. The Khuzaits are too mongolian and I wish they were more turkish honestly (Not every steppe society was the mongols durnit). The Battanians are, like, a slury of celtic cutlures from 1000 years of history. And the Aserai feel 6th or 7th century to me. But mashing together doesn't make a coherent historic equivalent to me.