Netflix said the fictional character is supposed to be north african but they casted an african american. In Norway, during Vikings era.
The fictional character is a viking father and an African mother he met on his travels.
The real life women isn't African American, she is an obscure swedish/Danish pop jazz singer (born an raised in sweden, moved to denmark). Similarly bi racial as her character, but the reverse, her mother Swedish, her father African (American? Not sure, she isn't really famous here).
The character insertion is total BS ofcourse, attention grab move. Possibility of intermingling tho small could been possible with well traveled raiders, but her taken over her father's Jarl role and it being accepted its total over the top fantasy lol (born and raised there could happened, trade hubs had people from unexpected places, but female and interracial being accepted as leader lol).
But as it been pointed out before, besides this casting (which btw if you watch the series, altho jarring at first, actually doesn't ruin it because so far its well acted and subtly used in relation to the leading characters) this franchise is so insanely liberal with the faux history part of the story it might as well be fantasy, the time lines (skipping century with some characters) and Liberal use of the characters is insanely flexible or made up (It still annoys me to see Leif Eriksson in raid/invasion party for England lol more then this minor Jarl character). Not to mention the magical/supernatural narratives.
But they nail most of the cultural or ritual aspects, and warrior customs (tho take liberties there too ofcourse), so there's plenty to appreciate in historical fiction nature.
But I would appreciated it more if this time period was made by HBO or something. Weirdly enough the history channel is the production that's least likely to have authentic historical narrative (i know this is offshoot is taken over by netflix now, but original series wasn't)