Someone said the turtle was alive, and for some reason I immediately thought of Discworld. I think it's totally plausible Discworld could exist in this universe. Probably in some place that was never conquered, like Allison's Earth. I could totally see characters like Granny Weatherwax and Captain Carrot as effortlessly being Royalty. (And double the pun with Carrot, there...)
Anyway--I did a second-take at the liberators after I read somewhere that the turtle is not a dead god but is alive, and I realized the turtle might actually be alive because Jadis is actually in there, in the glass pyramid atop the turtle.