Actual postage-stamp size being out.
yes, I'm running on fairy tales, but the sort of fairy tale where kings are literally neighbors -- so that one can look out the window and see his neighbor king's daughter -- pushes the story solidly into farce. Making them gentlemen instead works -- or, hmm, having a magical island where kings meet, negiotiate treaties, have their sons and daughters meet sutiable brides and bridegrooms, could work in some stories -- but neither one works in this story.
Got one kingdom within walking distance of another, since our heroine (and friend) made the trek, without being either exhausted or already athletic. Threw in a third for fun and giggles -- well, it can be at a point where three kingdoms touch.
Perhaps I should research all the Germanies. There were some pretty small ones.