Except the Sturgians are close to pretty much everyone who the OP posted about. They border the Battanians, Khuzaits, and Vlandians.
Yes, you're right and I don't find that as big a deal, so long as it isn't in huge numbers. But they don't border the Aserai.
And it isn't like people didn't travel far in history to take part in history, look at the Varangian Guard.
I know a little about them. From what I can find out, the majority of the Varangians stayed as soldiers and did not achieve the rank of nobility for at least a couple of hundred years, which is what this discussion is about. Many joined the Guard, got rich, then went home rather than assimilating. The highest social rank I can find a Varangian holding is Spatharokandidatos, which was equivalent to a court notary or low-ranking judge.
100 years after the Guard's inception, Anna Komnene was still referring to them as "axe-bearing barbarians", so that doesn't say much for the common assimilation of nobility from distant lands that we see in Bannerlord.
Fun fact: Bannerlord was almost going to have Varyagian Guard until they became cut content.
It doesn't really take mental gymnastics to see that this stuff is plausible.
When you see a truckload of culturally Celtic nobles strutting around as the inheritors of culturally Arabic fiefs in a 1000s setting, it definitely takes mental gymnastics to reconcile that imagery.
I would find it weird if a purely Arabic setting had Celtic nobility in there, yes. But I don't see Calradia as being too big for factions on the other side to have awareness and relationships with one another -- which means defections from across the way. My personal belief is that it is more or less Anatolia in size (which is plenty big) with roughly the same arrangement of cultures. So it isn't like having a Celt noble holding court on the Tigris River and more like someone from Thrace winding up in with the Mamluks in Syria.
I get what you're saying about there being an in-universe explanation, but my point is that a lot of people play the game for the way it resembles a real historical period, as opposed to the ways it doesn't.
And this
just doesn't look historical.
Of course, nobles of British Island (or Northern European in general) birth or decent have both campaigned, and owned land in the middle east throughout history - whether it was as representatives of the Roman Empire, or as parts of the Norman mercenary diaspora fighting for or trying to steal Byzantine lands, or as a host of various groups on Crusade.
"Throughout history" yes, but in this particular "600AD-1100AD" setting, no. The First Crusade was Frankish, German and Italian, with no Celtic armies participating, not even Brittany. See here the start and end locations.
Any small number of Celts who could theoretically have tagged along (I know of no historical mention of this) did not end up as nobility in the Middle East. Also this discussion is more about nobles joining another country through marriage and defection, not so much conquest or mercenary service.
It is entirely plausible as an alternative history setting, for a noble of Scottish birth to own land on the Tigris. There are plenty of real world pathways through which that eventuality might plausibly come about.
See replies made to Apocal and Phantom.
So even if you do see our game map as a larger faux-European size map, there is nothing anachronistic relative to real world history to see nobles from a northern latitude governing or fighting in a southern latitude.
So I don't give any credence to that kind of thinking. What is anachronistic, is thinking that high degrees of geographic mobility don't occur amongst adventurer warrior castes and societies through history.
Two massive overgeneralizations/false equivalences.
The true, but vague and irrelevant statement that some people from history from a "northern latitude" have once governed a "southern latitude" doesn't make it not anachronistic for a Celt to do so in a time period when it never happened.
This discussion is about established nobility, not the (again vague) category of "adventurer warriors".