There was an unified India just before 1947, and that makes the formation of Pakistan the partition of India.
It wasn't unified. The Nizam of Hyderabad ran a nation the size of Italy independently of the colonial administration in Delhi. He simply surrendered his foreign affairs to Delhi, but retained full control over domestic affairs including taxation.
The "myth" of Indian unity pre-1947 is a fabrication designed to eliminate the memory of obliteration of the Hyderabadi nation.
But we remember it.