[Ostrogorski]

Well, all Indo-European societies, more-less, were consisted of 4 castes:

Bramans - priest-educational caste

Kshatryas - warrior-ruler caste

Vaishas - merchants, craftsmen, workers, agricultural workers

Shudras - people who's only goal in life was to satisfy basic needs, like eating, sleeping and sex.

In difference with the "modern" societies, this traditional society was based on spiritual vertical, not material. Good and successful Vaisha could be wealthier than a good Braman, but Braman would still be a role model to everyone.