Glome is a fictional land supposedly well north of Greece, in an area in which there are many barbarian kingdoms. However, and very interestingly, the story can be dated with a fair degree of probability, allowing for literary license. The upper limit for it Apuleius's Metamorphoses. It is clearly implied that the Cupid and Psyche story in the Metamorphoses is based indirectly on Orual's book; she is writing for an unknown Greek, and the novel ends with arrangments to send the book to Greece. We don't know at what stage in life Apuleius wrote the Metamorphoses, but he died about AD 180. Apuleius wrote in Latin, but claimed to be adapting an earlier Greek text by someone named Lucian, and so Orual's book somehow is adapted by Lucian and then by Apuleius. This puts things more or less around the end of the first century at the latest. This can be confirmed in other ways. The Fox, who becomes the tutor of Orual and Psyche, is a Stoic philosopher who has been captured in war and sold into slavery and by that means come to Glome. He is very definitely Stoic, because almost everything he says is standard Stoicism -- this book would be a fairly easy way to introduce the topic of Stoic philosophy. And at one point, Psyche, in the course of describing the Fox's teaching, gives what is in fact a close paraphrase of the opening of Book II of the Meditations of Marcus Aurelius. Marcus Aurelius is a nearly exact contemporary of Apuleius, since he also died in AD 180 and we know that the Meditations were more or less composed in the last decade of his life. It is not, of course, plausible that Lewis is suggesting Marcus Aurelius as the source of the Fox's teaching, but it is entirely plausible to suggest a common influence. The Emperor was only writing a sort of philosophical notebook for himself, and often quotes and borrows from other authors in various ways. If one assumed that Marcus Aurelius was quoting or alluding to someone, then, one would take the Fox and the Emperor as having a common link somewhere.The whole thing is worth reading
In any case, while details do not matter, this is actually somewhat relevant, for in the Roman Empire, too, there was in this period a contrast like that which we find in Glome: the rationalist Stoics looking down on pagan sacrifices, and it was the Stoics who first came into sharp conflict with Christianity. (Both Epictetus and Marcus Aurelius criticize the Christians as fanatics, and Marcus Aurelius launched one of the major persecutions of Christians.) Like any good Stoic, the Fox understands the importance of civil religion; but he has no grasp of the sheer power of Ungit, and this is a severe defect in his otherwise excellent teaching. One of the more notable scenes in the book occurs when Orual is waiting in the House of Ungit to preside over a festival and she watches a peasant woman praying to the bloody stone that represents Ungit. Orual asks her whether she always prays to that Ungit rather than the Aphrodite-Ungit done in beautiful Greek style. And the woman replies that she does, because the other Ungit, the Greek one, wouldn't understand her speech, since she is the goddess only of scholars and the upper class of Glome society. It is an irony; the cosmopolitan goddess of the Stoics does not speak at so fundamental a level as the barbarian goddess who is worshipped with blood and sex, because sex and death are the matter of human life, and a goddess who can speak to ordinary people, and who can understand their speech, must be a goddess who understands sex and death. One can have both, but the people of Glome have no way of unifying them, only of putting them side by side; and part of Orual's difficulty is that she straddles both sides of the divide.
This reminds me that I should re-read Till We Have Faces. I remember liking it a lot, but at the same time feeling like the religious twist at the end was a bit of a cop out. Our teenage selves are pitiless, and I wonder if I would still think that now. (I'm being purposefully oblique now, but spoilers are allowed in the comments so if such things bother you, beware!)