The steppe way of war practiced by our earliest ancestors, and practiced by muslims today, is superior to the interregnum method of war, relying upon a concentration of forces. That means: RAIDS. Conduct of many small raids costs little but creates great uncertainty and costs the host thousansd of times as much in defense. In our past, we could retreat via horse, retreat to our forests, and the muslims could retreat to the deserts, or today retreat into slums and favelas. The value of armies is looting. The value of raiders is in imposing costs. One can, as has ISIS, graduate from raiding to looting, to decimating. But this destroys capital, and ensures your eventual defeat if you attempt to hold an economy and profit from it.