Not this argument again. Look, there are clearly female commanders, leaders, and strategists. It was often expected that the wife would manage the household/estates and settle business if the husband was away, indisposed, or whatever. But even Joan of Arc or Matilda, maybe even Boudica, Zenobia were not ACTUAL COMBATANTS, at least no primary source states it. How many representations of women in combat or female remains with combat injuries are there compared to hundred, THOUSANDS of representations of men? There are some eyewitness reports of female fighters, particularly from Romans fighting celts, but these were likely acts of tribal desperation rather than what a more 'civilized' military force, particularly one of occupation or raiding, would do. There are also reports of celtic women attacking and killing their own men who were retreating, then they killed their kids rather than see them enslaved by the romans (I'm thinking of Aquae Sextiae but I'm probably confabulating accounts).Though female warriors certainly were not the norm during that period there are numerous example of them in medieval Europe. Matilda of Canossa is an example and I'm sure you've heard of Joan of Arc. There is also recent archeological proof that women (or at least this woman) fought for Vikings in Sweden, as she was buried with a full weapon set next to a garrison.
There are also examples of non-white people in Europe in warfare during that time period. You are probably aware of the Moors, who conquered most of Spain and Portugal.
You should not let this sort of thing detract from your enjoyment of a work of fiction. If its good, then its good regardless of the sex or race of the actors.
Anyhoo, speaking for the viking era in particular, you'd think there would be ample primary source evidence for any significant numbers of women in battle, or foreigners mixed in with their units. But there isn't. Taking very rare contrary examples as justification that "it must have been common" is a fallacy. Granted, we may never know the truth as we are always looking at very selective slices of history.
But before dismissing it all, just consider if this was the next "non-documentary" fiction movie about Shaka Zulu...
or if this was how they depicted Miyamoto Mushashi at Ganryu Island...
I mean, if it is all fictional, then nothing really matters, right??