Affiliate Marketing Secrets

The majority of the Pashtun Population live in Pakistan. Most Pashtuns are ‘Pakistani’.
But what I have noticed with Afghans born abroad (Or from Afghanistan) is that they seem to be very affiliated with Persians & Hang Around With Them and are more involved in their communities than they are with Pakistani Pashtuns –
Whereas Pashtun Pakistani’s generally hang around more with other Pakistani’s or even Indians.
So I just found it confusing because they are both basically the same (Except for countries) – So why is there so much segregation between Afghan Pashtuns & Paki Pashtuns? Anyone who can fill me in on some clarification – I will be greatful.