Well, in all (predominantly) non-literate and/or pre-literate societies, I think the role of a keeper of lore and, specifically, genealogies, was fundamental for all kinds of reasons – kinship, marriage, inheritance, rights to succession, and so on. By literate of course, I mean as in writing/books as we know them, naturally, iconography and symbolism can also convey meaning, too, and I believe that in many cultures art was not merely decorative or aesthetic in function, but also symbolic and carrying meaning – stories, lore and suchlike. In Mediaeval Europe, heraldry evolved as a way of indicating family, genealogy and heredity, too – most people, certainly the poor foot soldiers on a battlefield, would not have been literate at the time. I’ve heard it said that a church from the Middle Ages, is like a book in stone, everything has a meaning. It’s a really interesting subject.