Does this imply that there is a possibly that Brahamins of India are populations with the "Pakistani" genetic component who migrated through the subcontinent when the climate changed in modern day Pakistan? Some migrated East while some stayed, likely with a reduced population due to reduced carrying capacity of the land. Population then rebounded when climate conditions improved.
It adds credibility to Pakistan being the inheritor of the IVC and its decedents still living in Pakistan today with a portion of the ancient population dispersed in the nation state of India as Brahmans who mixed with the local population.
Centuries after the collapse of IVC in Pakistan, civilization the Ganges rose, possibly due to the IVC migration.
This implies a few things:
a. Aryan migration from the west into the Indus Valley indeed occurred beginning in 1800 BCE.
b. Aryans merged with the Harappans over a period of 450 years, giving rise to Indo Aryans in around 1500 BCE. This led to the formation of Vedic Sanskrit, Vedic tribes and Vedic religion or in essence the "Vedic civilization".
c. It appears all the Vedic clans and kingdoms arose at the same time and thus there was no 1 powerful kingdom to wield everyone together. This is what eventually led to the "Battle of Ten Kings".
In the Vedas, a famous battle is said to be have place in 1300 BCE between a confederation of ten tribes and the Bharatas tribe along the River Ravi in Punjab. The Bharatas tribe emerged victorious, BUT the battle was so heavily fought that neither side actually won.
After that battle occurred, the Bharatas are said to have left the Indus Valley and migrated into the Ganga along with there allies (the Kurus for example), while the majority of the tribes remained.
This is where confusion arises. The "official story" is that the Bharatas and there allies took control of the Ganga and wrestled power away from the native Ganga inhabitants, who at that time were the Dravidians. They then wrote the Puranas, Manusmiriti and Mahabharata and pushed the Dravidians into the south. This myth has remained to this day.
Genetically however, this isn't the case at all. From what we can see, North Indian populations are indistinguishable from South Indian populations, who are Dravidian. This means that the current North Indian population are descendants of the original Ganga inhabitants, and hence Dravidian as well. This then obviously means that the Bharatas tribe and there allies must have merged into the local Ganga culture and peoples.
It's this merging which formed what we call Puranic Hinduism or Brahmanism and out of this Vishnu, a Ganga god.