Agreed that India is not a single entity, and I'd add that Pakistan is not that integrated either. Those Pashtuns in the North-West Frontier Province do take great pains to distinguish themselves from the Punjabis in the East, and the Balochis and Sindhis in the South. I suppose I shouldn't leave out the Kashmiris.
Now as to not having things in common, I have to disagree. There is a distinctive desi-ness to our affairs, which in my eyes still binds 'Maula Jatt' and 'Endhiran' as belonging to more or less the same culture. Just my opinion.
As a South Indian, there are not many things common between me and a Pakistani.