"It worked."
The world view for most powers in those days was that it was clearly a higher moral choice to ensure the survival of your own people by wiping out a rival than to engage the Brotherhood of Man, universal human rights, etc. in fashion today - a natural point of view really, in a world that relied utterly on slave labor, which necessarily negated any idea of universal rights. Of course their mutually-geneocidal impulses were largely kept in check by their logistical limitations. Even Rome had limits to their ability to project power, as later was true of the Mongols, the Turks, the Aztecs, and all the other would-be dominators.
I agree to an extent.......most ancient cultures were titular monarchies for the most part, until Greece came along, and typically the leadership either migrated through bloodlines, or internal conquest. Essentially the survival of the fittest (or most feared) attained leadership by whatever means was available to him/her. Reading between the lines of ancient history yields the tacit conclusion that many in leadership of these societies were murderous psychopaths, and projected power on the basis of their egos, desire for additional lands, resources, wealth, or just plain power (the Khans come to mind). Religious differences were relative latecomers into the equation, but the bottom line seemed to consistently be to "never leave an aggressive enemy on your borders", ergo some form of continued conquest was necessary to maintain a balance of power in a given area, and to ensure the continued security of your particular cultural group.
This model continues to be seen today in sub-Saharan Africa, following the end of the colonial period, this continent has reverted, to a great extent, into its former pattern of tribal wars over issues as important as resources, and as insignificant as relative ethnics, or religious differences. Genocidal conflict is common, when the goal is to project a given cultural influence, as well as protect your own. Simplistically, the best way to accomplish this goal is to completely eliminate the competition, rather than allow it to fight an expensive war of attrition next door.
We in the west have, to an extent followed the Greek model, which, if one recalls the lessons of history, only worked for a while, as it did for the Roman Empire.......although "enlightened", and "morally humane", it will only serve so long as it is supported by the ability to project massive amounts of destructive power if necessary, and the (assumed) will to use it also if necessary. Which, in the instant sense brings us to the real danger of modern liberalism, which threatens to remove the fangs from the tiger, so to speak.......if that ever happens, we, as a society are doomed to repeat the fate of those that have done the same in the past. The ancients taught us (and we should always remember) that it is far safer (for a given society) to be feared, than loved, by the rest of the world.
doc