Religion, manifest destiny, social gospel, social darwinism, etc. They tried to claim it was in the bible and also poor people were poor because they were uneducated and lazy and rich people were rich because they are educated and deserving of the wealth. Also the poor people needed to be "weeded" out because they were hurting our species.
I don't believe you question was full , but i do know T<span>he nomads of central Asia impacted the other global civilizations of the Eastern Hemisphere in the postclassical era in </span>1200 to 1400