pak-one
Your statement is as stupid as someone saying Urdu-Hindi and Punjabi speaking people in India are Pakistani in culture and identity.
You have a very extremist Hindu Akhand-Bharat mentality.
Who says Punjab and Sindh are "Indian in culture"? Punjab is Punjabi in culture, and Sindh is Sindhi in culture.
The presentday Republic of India is just an artificially created country (much like our Pakistan).
India today is just the name of a republic, it does not represent any culture or group of cultures outside India.
If anything Pakistan is more ancient than India, we were created before India on the 14th of August whilst they were created a day later on the 15th.
In the past India or Hind was simply a geographical label synonomous to the term South-Asia today, it did not refer to a country and culture in those days as even today both these countries are very culturally and ethnically diverse.
There is a difference between the presentday Republic of India and the Empires which ruled these areas in the olden days, all the empires which united this area politically in the past were mostly foreign, some even say Chandragupta Mauraya was from Nepal or Swat (in Pakistan) and not from presentday India.
As hellraiser pointed out presentday Pakistani lands were only part of the same Empires as presentday Indian lands for only 711 yrs out of which 512 yrs were under Muslim rule the remaining under Buddhist and Christian rule.
Whatever history falls in their lands is their history, whatever falls in our lands is our history and some history we both share.
Some Pakistanis might have followed a Vedic religion (ancestor of Hinduism) in the past for a period of time but even that did not originate in presentday India, it was brought from outside by Aryans just as Christianity and Islam were introduced to the region from outside.
The only similarities we Pakistanis have with India are linguistic similarities with Indian occupied Khalistan (East Punjab) and the Urdu/Hindi speaking regions.
We have nothing to do with Tamil, Telugu, Malayalam, Assamese or even Gujarati, Bengali cultures in India.