According to a new study on an IVC ancient DNA, there was no European component in the genetic makeup of the Rakhigarhi individual dated around 2800-2300 BCE. The Steppe component appeared 2000-1500 BCE onwards. During this period, Indus Valley Civilization was in total decline.
According to the authors, this IVC component is still the biggest among Indians. So, evidently, after the decline of the IVC, the people still survived. What would have been their condition? Most likely their society might have been in a disarray. There would have been no proper political structure and there might have been chaos. This would have been an ideal time for an invading group to impose itself politically and culturally on a people who had lost a unifying identity and political leadership. A similar situation one might observe throughout our history.
What we observe in the early stage of the caste system is the dominance of Indo-European deities. However, in due course, those deities became minor. The new dominant ones like Shiva and Vishnu appear to be an assimilation of native traditions with the Vedic tradition but within the caste structure. In my opinion, there could have been two exclusive phases in the interaction between Indo-Europeans and the IVC people.
- Broken IVC people enabling the IEs to impose their culture and create a caste system with themselves in the highest position
- Re-emergence native traditions which were then assimilated with the Vedic culture. However, without changing the caste hierarchy (though only Brahmins matter)
We can observe that this became a template for Brahmins wherever they migrated in the subcontinent - keep the caste hierarchy and assimilate the native traditions with the Vedic culture.
The only way to describe a situation where outsiders imposed their culture on the natives and kept themselves at the top of the hierarchy is "invasion".
