You still have to have loads of humans to man those walls, along with paying them and the associated logistics. Firearms weren’t too great a range until the 20th century.
You could control choke points, but nothing was stopping a random dude from walking in through the forest or desert.
sbeak@sopuli.xyz 1 day ago
Smuggling was a thing back then, right? Paying someone to help you navigate the not so hospitable and easy-to-get-lost-in deserts and forests.