The Old Kingdom is set in another dimension from Ancelstierre.In Abhorsen, Mogget says something about the Seven Bright Shiners "intruding on a dimension not our own." The Old Kingdom, more properly, is a small parasite dimension (only the size of a country) that is attached to Ancelstierre, and whose other borders are indeterminate. The Wall between them does not force the seasons and phases of the moon to be different; it just stabilizes the link between the two worlds. What happened to the rest of the dimension? Orannis the Destroyer, in all likelihood...