I see some confusion about the meaning of "barbarian" intended in Rands' essay.

Rands doesn't mean barbarian in the classical Greco-Roman sense.

Rands is referring to a barbarian vs. civilized dichotomy used by more recent historians such as Ibn Khaldun.

Khaldun in his _Muqaddimah_ laid out a model of historical cycles based on the idea that so-called 'barbaric' tribal peoples cultivated strong social cohesion or group solidarity (his exact phrasing in Arabic does not translate into English with unambiguous precision.) When a people is living in a rich civilized land, the people loses its tribal-style cohesion and solidarity against conquerors. This gives rise to a recurring cycle in which civilized lands are conquered by tribal 'barbarians' who become a new ruling class; the new ruling class becomes decadent and unable to cooperate effectively against invaders, and the cycle restarts as a new barbaric tribe conquers the civilized land to become the new rulers.

Khaldun's model of this historical cycle favorably impressed many historians centuries later, and has caused some to call him the 'founder of sociology.'