Vance builds the history of his world using layers of facts, names and religions taken from various European cultures – Greeks, Romans, Celts, pre-Carolingian French and Spanish "kingdoms" etc., and adding in places and peoples imagined by those same cultures – Atlantis, Ys, Avalon, Fomor and so on. This fantastical/factual mix is used to ground his tale in "history". It also seems to give some of the same depth that a longer series of books might develop where place, relationships and plot are built up over time (as in Thomas Hardy's "Wessex" or Trollope's "Barsetshire"). It seems to provide the believability that develops where a story is set in a well-known, well-defined historical setting as if the reader holds merely a hitherto untold story.