[X] Plan Roaring Forge, Iron Sea
So they built to tank it. And thats also why they had small forestries and farms in the wall bounds too. It was expensive to build, but the environment did reward it.
Its mostly because of defending against nomad invasions AND early chinese gunpowder. The walls are rated for gunpowder because before there were cannon, walls were sometimes breached by literal barrels of gunpowder.Although as far as defences go, @veekie's mention of Chinese cities had me looking up Chinese city walls on Wikipedia, which was interesting. Apparently with a predominantly earthen construction at the core, Chinese city walls were capable of withstanding even early 20th century (!) artillery with little damage because they were so ridiculously thick and robust. Something to think about perhaps.
So they built to tank it. And thats also why they had small forestries and farms in the wall bounds too. It was expensive to build, but the environment did reward it.