Flesh.
Historical reference: The story takes place in ancient China just before the Tang Dynasty. Cannibalism had become a way of winning the war as well as surviving the starvation the war was causing. It seems to have begun when a general fed his wife to his starving soldiers. They didn't want to but they had no food. They didn't seem to mind after that, and women and children of villages they conquered became their sustenance. This way of survival spread to other camps and other sides of the war. It had become such a problem that when the Tang Dynasty came into power, they had to create a specific Imperial Law forbidding it.
I don't address all of that in my story, but it is a characteristic of an enemy tribe. The main villain is a disturbed psycho obsessed with my FL, too.