Tis' a shame this was axed, it's rare to see manga ballsy enough to have an unequivocally evil MC that isn't just straight up murder-edge-cackles-maniacally, and we can also see at the end here that the author had general a plan for the whole story too, so he wasn't just winging it.
You can tell the author put a lot of thought into his story, actually stopping to think about the realpolitik of the whole thing, though it is a shame he decided to make the protagonists more akin to bandits than something like the Mongols, it does seem he saw that terror worked in a war, but not why or how it worked.
Anyways, it's a shame well-thought (even if not perfect) stories like this get axed while generic trash keeps getting shat out by the thousands every year.