Greetings!
My understanding of the assignment would be that you are to look at the historical details the author provides and essentially test their accuracy by looking at research that has been done. For example, in the novel, a large banquet is held and the nobles are described as eating with knives and forks. You could search history books and scholarly journals to discover whether that is an accurate portrayal of utensil use. If the novel is set in the 4th century, your research would likely show that forks had not yet been invented; thus, the novel contains an historical anachronism.
Because you are discussing whether the setting is accurate or not, I would consider that "criticism." You are giving your opinion based on the supporting evidence.
I hope this clears it up a bit!
Thanks,
Sarah, EssayForum.com
Sarah, EssayForum.com