Put this in mind though, "野蛮战胜文明" only happens when engaged army have no conspicuous weaponry differences. A bravely sword-carried calvary charge would fail to a well-trained rifle infantry formation, for example. In fact, the northern nomadic tribes had advantages over the central plain army in some fields back to China's ancient time. Horse breed comes to mind. In addition, the "barbarians" learned forging technology or alchemy from central plain, while they obtained central plain military materials via trades.
From a soldier's perspective, the reason why he or she fights a war has huge impact to the soldier's contribution in a battle. The battle is most likely won if all of the soldiers hold the same belief. I agree that the "barbaric" lands had little attraction to the "civilized" central plain people.
By the way, I am glad to see your writing again.