Rule of Thumb----Hindus is basically Indo Aryans + Dravidians with other races being inducted much much later
People of the Indus Basin are not only Indo-Aryans but also are the recipients of multiple-pulses of later nomadic Indo-European genes like Persians,Scythians,Kushans,Wusuns,Yuezhis,various hues of Hunas.....
Even Mahabharata itself (400 BC-400 AD) said that the Indus basin region was not fit anymore for Vedic sacrifices because of intrusion of Mlecchas
'There where forests of Pilus stand, and those five rivers flow, viz., the Satadru, the Vipasa, the Iravati, the Candrabhaga, and the Vitasa and which have the Sindhu for their sixth, there in those regions removed from the Himavat, are the countries called by the name of the Arattas. Those regions are without virtue and religion. No one should go thither. The gods, the pitris, and the brahmanas, never accept gifts from those that are fallen, or those that are begotten by Shudras on the girls of other castes, or the Vahikas who never perform sacrifices and are exceedingly irreligious.'
The Mahabharata, Book 8: Karna Parva: Section 44
Because of having equal association with later nomadic Indo-Europeans as with earlier Indo-Aryans, people of the Indus Basin chose MOSTLY trans-national religions like Buddhism instead of Hinduism.
That's not to say that Central Asian nomads who settled in Indus Basin never converted to Hinduism..Quite the contrary..Examples abound such as Northern Scythians and Alchon Huns. But their level of piety and religiosity were no where close to say that of the Indo-Aryan Brahmins. The Heavy enforcement of Hinduism was missing during those empires
There were pious Hindu empires in the Indus Basin from time to time though, but they were manned by super pious Indo-Aryan Brahmins rather than nomadic converted Hindus...
Chief example of such a dynasty would be the later Hindu Shahis from 850 AD to 1001 AD..who were estimated to be Mohyal Brahmins....
Around 17.5% of male lineages in Northern India belong to the Indo-European pool..Compared to that by my estimation, around 40% of the male lineages in Pakistan belong to the Indo-European pool....
This 20% difference in IE lineage will of course show up in how the two peoples will identify themselves..This subject requires a nuanced and patient view....
When I referring to Pakistan, I am referring specifically to that part of Pakistan that lies between the eastern bank of the Indus and the Indian border...The Western part of Pakistan is beyond the scope of the Indic cultural sphere.
and I have given ample evidence from pre-Islamic times to avoid any needless religious confrontation...
Indus Basin was slowly differentiating itself from Eastern India by adopting the successive innovations of Mahayana Buddhism..Swat itself played a major role in Transmission of Buddhism into Central Asia...
If there was no Islam, Pakistan would be Buddhist and still would be cold to us akin to Sri Lanka ..(though the modern enmity would largely be missing).....Way more Buddhist stupas are found around Pakistan than ancient Hindu temples
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