Because Pakistan had its own strategic importance unlike india pakistan never was a dud land.
IVC actually was the ancient Pakistan.this was the reason hindu were never allowed into IVC.because in Pakistan only pure people were allowed.this the only reason why Ashoka left hinduism.just to enter into Pak.ancient Pakistan.
Pakistan never was a part of india.this is the reason Pakistani and indians are different people.
Pakistan is not merely a race but a state of mind.
Pakistan was merged with India because of foriegn invaders.
Because of Jinnah we humans got seperated from indians