Whenever I see ilustrations of ancient city-states or medieval castle towns, I see a similar picture. A walled semi-urban structure surrounded by huge plots of agricultable land. I wonder, in case of an attack wouldnt the lord of the lard or ruler want to protect its farmland aswell? Wouldnt it be against his interests if a warband burned his fields and killed cattle? I know that building stone walls around the entirety of the rural areas would be impossibly expensive but why we never see large palisade walls or defensive structures around farmlands?