U have to consider the world was never the way it is today And it changes moment by moment. If a person lives long enough, then suddenly they are aware of the changes. But every day they doan see those changes.
The ancient world(on this particular topic) had the Hittites and the Dravidians. The Hittites expanded their borders from Anatolia well into todays India, pushing the Dravidians more and more into the southern regions-where the Dravidians encountered the TRibal people of the south. Eventually, the conquered became conquerers-imposing the Hittite culture of gods and goodess(Indra being the King of the gods) and even the sari-for they lived among the conquering Hittites.
The Aryans would come much later, also with their gods.The Aryans brought the notion of holy men, namely the Brahmins who knew all the chants to appease the gods. Conquering the Indus civilization, and later moved along the River Ganges to other communities they would impose their systems of life. Castes.
By the time the Brahmins reached south india, the Dravidians were a force to contend with.
The religious practices of the Hittites and the Aryans merged into the beliefs of the Dravidians making the Tamils a race of people that built huge monuments(temples) to the gods.
Some of the temples exist today,under British rule the hid it
due to some of the carvings,the people were highly advanced
i saw a documentary on National Geographic about the temples
built when Raja Raja ruled.