Reposting here from another thread: Just to keep the threads separate and more specific.
The guys of NWFP are an everchanging set of people - they move eastward as they get displaced by a new set of people.
Using just approximate dates,
In 2000 BC it was IVC people. They mostly vanished, though some must have persisted in low populations
In 1000 BC it was Aryans. They went East.
In 500 BC it was Iranians (Acheminid Darius the Great). They were a tiny minority but gave us writing - and mainly went back to Iran
In 300 BC it was Greeks - and gave us proper writing Brahmi. And Ghandhara culture
In 200 BC it was - for the first time from East to West - Biharis (Ashokans). They made the whole area Budhist
In 100 BC it was the Parthians
In 0 AD it was Shakas
In 100 AD it was Kushans
In 300 AD it was Biharis (Guptas) again - who for the second time went west from east and pushed back the Budhist Kushans (Kayasths) and Shakas (Rajputs) west from northern India.
500 AD it was Huns
From 700 to 1200 AD it was the Shakas (Rajputs) who came West from north India into the Punjab and NWFP for the third time in history (after they had mingled with the local Indian populations
In 1200 AD is was Afghans and also Mongols.
In 1400 it was Turkmens
In 1500 it was Mughals
In 1700 it was PErsians
In 1800 it was the Sikhs who for the fourth time came West from northern India into NWFP
The NWFP has never had the same set of people or the same culture or the same religion. Punjab was similar - it was a melting pot of all kinds of nationalities and cultures and religions. Nothing is fixed.
And they are all mixed up with the north Indian people.
As I said above, there have been four times in history when people from India went into Pakistan - and maybe including the original IVC people that is 5 times where the genetic material came from the subcontinent - and maybe 10 times that genetic material came Iran, Parthia (Herat and Turkmenistan) and Uzbekistan.
Iran, Parthia, Turkmenistan, Uzbekistan and Kyrgizthan are all deserts with low population levels. The people are vigourous fighting tribals but never populous. Even Iran's recent population explosion is if very recent origin.
Population is only achieved in the plains like Syria, Iraq, Punjab.
So in the genetic mixture, people from the more populous agricultural settlements are always more likely to predominate vis-a-vis the smaller tribal rulers. For example, the peak population of IVC is likely between 2-5 million people - more than Egypt and Mesopotamia put together - and that was 4000 years ago.
The tendency for massive population increase is in the Punjab even now - Balochistan and NWFP do not and can never support the kind of massive populations which the Punjab can.
Who are the Pakhtun?
The pathans are probably maximally derived from parthians. They were from Turkmenistan and Herat region and dominated and invaded most of the nfwp and afganistan.
The parthians were famed in historical records for extraordinary fighting ability. They ruled much of iran afghan and nwfp 2000 years ago.
Their two main accomplishments were cavalry without stirrup and the parthian or parting shot from the bow (the famous composite bow)
After decline of the empire pathans continued to be famous for being spartan fighters. They invaded most of nwfp after the decline of the empire when they had left iran behind.
Theh were never Hindu. They were Buddhist for a long time and then muslim.
They have their own culture and mostly absorbed the later influx of kushans and huns and uzbeks and mongol blood while preserving their culture.
They were of course famous fighters even in British times and in current times against russians and now americans.
The mughals also faced continuous trouble on the border from pathans. A heavy garrison was always sent from Delhi to man the borders and mughal empire never really controlled the nwfp for any length. In fact Parthians werent living in afghanistan at all when Ashoka ruled afghanistan. After the parthians came to afghanistan nobody has ever ruled over the parthian people at all except for brief military victories. Which is pretty extraordinary.
Of course most of the army sent to man the borders in mughal times were of local indian muslim converts only. So the biggest westward flow of indian blood into nwfp ocurred during the mughal empire.
By now some 50 million in afghanistan and another 50 million in pakistan must be pathans. Even if my numbers are wrong there must be 60 million plus pathans in the world. That is bigger than iran or egypt and dwarfs any other muslim country in the middle east.