I wouldn't really consider the early Vedism developed in the Indus region as "Hindu". The two were far too different.This adds an interesting Hindu based religious reality to our region.
The Vedic tribes of the Indus region sacrificed cows along the Indus, followed a tribal system identical to the Biradari/Qabeela social structure in Pakistan as opposed to the caste system in India, considered idolatry as taboo, primarily revered a completely different pantheon, did not believe in core Hindu doctrines such as reincarnation or avatars, etc...
I recommend reading up on this:
Here are excerpts that may intrigue you:
The difference is huge. In fact, some scholars argue that modern-day Hinduism can barely be called a continuation of Vedic Hinduism at all.
An exception may be the cult of Shiva, which is theorised have developed from the cult of Rudra or another Vedic deity (there are several theories). Rudra is still used as an alternative name of Shiva.
Currently popular gods: Rama, Krishna, Kali, Ganesha, Hanuman, Brahma, Vishnu, Shiva, Saraswati, Lakshmi and Shakti.
Popular during Vedic times: Indra, Agni, Soma, the Ashvins, Varuna, the Rudras, Mitra.
A few other beliefs that differ:
Reincarnation: Reincarnation is not really attested in the Vedas, although they hind at life after death. This removes the very foundation of modern-day Hinduism.
The caste system: The Vedic era didn't have a rigid caste system, although some verses of the Rig Veda were later interpolated as giving religious sanction to the idea.
The taboo on cow slaughter: The Vedic scriptures contain descriptions of people both sacrificing and eating cows.
The doctrine of avatara: The concept of divine avatars, important to modern Hinduism, is not to be found in the Vedas.
The Bhagavadgita, Ramayana, Mahabharata and Puranas: These scriptures and the doctrines they contain all postdate the Vedas, and by far outweigh them in importance today.
The term 'hindu' itself: The people Vedic people did not call themselves Hindus. The term is commonly applied by non-Islamic sources only from the 15th century.
So, basically, you have two religions with pretty much nothing in common except veneration for the Vedas. They are much more distinct than, for instance, Judaism and Islam.