"I'm really asking about the economics of imperialism - what is the Southern contribution to value production?"
They're net exporters of capital, they're arms markets, they're dumping grounds, they're sources of cheap labor and raw materials; they give the military practice opportunities. They also provide a bleak picture of what it's like to be the ultimate underdog, making the plight of the most abject beggar in the North, enviable by comparison.
Does this add up to "value production"? I don't know because I don't know what "value production" is.
Joanna