The Force-Oh! So you're from Luke's world then. [Now she has a better understanding of what he meant before about his world being more futuristic.]

It might be another protective measure for the north I think. What with all the dangers to the Old Kingdom why not just destroy everything up there and rebuild? But guns, tanks, and heavy artillery fail when they near the wall which would make any such effort impossible. Most people deep in the south simply refuse to acknowledge there is anything odd in the land to the north at all.