Though they were of different races, and the distinction was marked and brought home to themselves by the contrast in the colour of their skins, it seems probable that the real basis for their antagonism was not social so much as religious.

The Indians were hated and despised by the immigrants as the worshippers of a hostile god.

They could not join in the sacrifices by which the Aryans held communion with their gods, and the sacrifice itself could not even be held, in theory at least, except in those parts of India which were thoroughly subdued and held to have become the dwelling-place of the Aryan gods.

The proper course prescribed by religion towards the indigenous residents was to exterminate them, as the Israelites should have exterminated the inhabitants of Canaan.

But as this could not be done, because their numbers were too great or the conquerors not sufficiently ruthless, they were reduced to the servile condition of impurity and made the serfs of their masters like the Amalekites and the plebeians and helots.
If the whole of India had been thoroughly subjugated and settled like the Punjab and Hindustan, it may be supposed that the same status of impurity would have been imposed upon all the indigenous races; but this was very far from being the case.