The problem with spreading our social order is (a) demographic distribution and

The problem with spreading our social order is (a) demographic distribution and (b) degree of civilization.

In practice we should see Aryanism (markets for rule) expandable only into areas that did not have the ability to expand the underclass, and did not possess a large underclass, and face little tribal conflict.

Conversely we should see the worst behavior among peoples who have expansive underclasses, the agrarian or pastoral ability to expand those underclasses, and lots of territorial competition from other kin groups.

And that is what we see