and jixed Before the advent of Islam, the majority of people in the region of Pakistan practiced Buddhism, Zoroastrianism (and its derivatives like Mithraism, Saurism, Manichaeism, etc.), Animism (nature worship) including Greek/Hellenic Paganism, Shamanism and other deities.
2nd Harappans ate beef, buried their dead, and had no "Hindu" temples/idols/deities so majority of punjabis were buddiusim ..
3rd Mauryan Ashoka introduced Buddhism.
Buddhism was later also propagated along with Zoroastrianism, Animism, Shamanism, and Hellenism under the Bactrians, Sakas/Scythians, Parthians, and Kushans for many centuries.
The pre-Muslim ancestors of most Pakistanis never called themselves "Hindu" nor practised any religion similar to present-day "Hinduism". Thus, the pre-Muslim ancestors of most Pakistanis had nothing to do with so-called "Hinduism".
The fact is there is barely any trace of "Hindu" past in Pakistan region yet there are plentiful of Buddhist and other non-"Hindu" archeological remains in Pakistan region.
When Muslims invaded Pakistan region the majority of its people were Buddhists (as testified in Chachnama), so much so that the word for idol became "budh".
The word/term Hindu/Hinduism is a recent construct. It were the Muslim invaders (Ghorids) who for the first time in history imposed the foreign term Hindu on the many different, unrelated peoples and religions of south Asia. The term Hinduism was given by the British colonialists. Not a single pre-Muslim/British era Vedic, Brahman, Buddhist, Jain, or any other South Asian scripture/inscription mentions the word Hindu/Hinduism. Similarly, Sanata Dharma was a term invented in the 19th century AD by Gangetic Brahmans in their desperate attempt to replace the Muslim/British term Hindu/Hinduism.