This is the reason for my question. The whole paragraph is about trade goods from afar. I have heared about everything the author mentions except jute ropes. So is this just idle talk or really fact?
"Prize-winning poet Shelley Puhak is the author of the new book The Dark Queens, from which this story is adapted."
I don't know if the author is a historian, and she doesn't present herself as one. I'd take that into account when reading the article/story.
I would also add that it's not likely that someone would bother transporting slaves in wagon carts, especially in 6th century northern europe.