There are 33 Vedic tribes listed in the Rig Veda.
Their presence and dispersal was towards the north,north east of India,Persia and Russia.
One has to account for the presence of Sanatana Dharma in the Far east ,extending to Australia and the spread in Europe,Africa,Americas and Mesoamericas.
This was the work of Dravidians at first and later by the Vedic people.
Probable that Agastya brought with him Brahmin families as well and they might have settled in the Konkan Region, Goa.
There is a view that Parashurama brought them to the South.
Saraswat Brahmins lived on the banks of now-extinct Saraswati River that flowed in the northern part of India. They derived their name from either the river or from their spiritual leader, Saraswat Muni. who lived on the banks of the Saraswati.
The River Sarasvati is included in the Prokshana,Sandhyavandan and Snana Mantra..
Gange cha Yamenes chaiva Godavari Sarasvathi,
Narmade Sindhu Kaveri Jalesmin Sannidhim Kuru.
There was a Vedic civilization flourishing on the banks of the Sarasvati river and it was named as Sarasvati Civilization.
Initially all the references found in the Vedas,Puranas and Ithihasas were dismissed as Myths.
As science advances and the web becomes the source of information , which has been not available earlier, the Myths are found to be facts.
During my professional Life, I have covered India extensively and had partaken food with the local people in Kashmir,Punjab,Bengal,Odisha, Gujarat, MP, UP , not to mention the southern states.
What struck me was the essential food habits are the same, right from offering water first to the householder eating later.
Major difference is that in the Northern States Wheat is consumed in place of Rice.
(Rice is consumed more in the Southern States of Kerala, Tamil Nadu,Karnataka, Andhra,and in th East Bengal and Odisha.)
Yet for Religious ceremonies Rice is being used and the vegetables that are used all over the country for important ceremonies like Sraddha remain the same.
Still we cling to 5000 BC as the bench mark,the date assigned to the Rig veda.
The Riwatian People of India date back to 1,900,000 BC!
Many skim the eastern part of India when studying Indian History,especially that of Bengal.
Surprise in store.