I am doing double major. My second major is the Archaeology and my focus is on Indian-Subcontinent.  While doing my research on ancient tribes in Indian sub-Continent i came across this site which describes about some ethnic tribes in India and about some information that is related to Hinduism. More interestingly this ethnic group is associated with the ancient Kirata people.
While doing research on ancient tribes of India, their culture, customs and practices, one can easily identify that Hinduism revolves around these ancient tribes.

For long time now scholars were puzzled with the Hinduism. There were no exact founder of religion of Hinduism and the unexplainable of being thousands of Gods in one religion. But lately, people have beginning to understand the meaning of Hinduism all crediting to the scholars who have studied on ancient Indian tribes. Lately, foreign scholars and historians have beginning to understand Hinduism much better and has label religion of Hinduism as a "Borrowed" or "plagarize" religion.
But concerning to me, i said that it is a derivation of tribal religions.

http://www.himachalindiatourism.com/people-of-himachal.htm

The State And The People:
The beautiful hill state of Himachal Pradesh lies at the foothills of the Himalayas. The mon khmer (Kirat) and other tribes had sought shelter here when persecuted by the Aryan invaders. Shanwar was their brave and powerful leader. This proves that this tribe exited as far back as the Rig-Vedic (early vedic) period. In the second century B.C. this entire area was known as Kinnar, the land of Kiratas. Proofs for this are available In the famous stone edict (in the Sharda script) found in the Shiva temple at Baij Nath. The edict refers to the settlement as the 'Kir' village (Kirat Gram). These tribes have now settled in the Lahaul-Spiti, Chamba and Pangi areas. In the Malanga village in kulu, we have distinct proofs of the Kiratas having settled there.

In the tribal area of this region one still comes across prehistoric socio-cultural beliefs. The Kiratas, the Yakshas and Nagas here are among those important tribes to which we have parallel references in the Puranas and history. According to these the forerunner of man in the universe, "Manu lived in Manali (Manavalaya, the abode of Manu). The oldest temple of saint Manu is located here. Other rishis too performed Tapas here. Ashramas of some of them like Vashishtha, Vyasa asn Bhrigu are located here. All this proves tha this area has a long historical past and it has performed an important role in the rise and development of the human race.

From the topographical point of view, this area has been referred to as Trigarta, an area separated from the plains of the Punjab by its peculiar physical characteristics. It had six Janapadas known as Trigarta Shashtha or Jalandharayana. The present day districts of Chamba, Kulu, Mandi, Bilaspur and Kangra come within this Trigarta area, well known in the hill regions. It was also called the Ayuddha Sangha, a federation of six principalities.

There are also indications that the Aryan Rishis of yore preferred to live in cooler climates, in area lying between Kashmir in the west and the coastal regions of the Sutluj river in the east. The Rigveda calls the Vyasa river 'Arjikiya'. In this area are also located the remains of the eight storied temple of the saint temple of the saint Shringi and Skirntila, the site where the king Dashrath is said to have performed the Putreshti Yagna (the fire sacrifice that helps produce a male heir). It is also said that the saint Bhrigu had brought the fire God Agni down from the heavens in this very area. Perhaps Parvati, the daughter of the Himalayas, also belonged to the area. There is a river called the Parvati in the Kullu region, after which the valley is known as the Parvati valley. This perhaps was also the domain the King Daksha, whose daughter Sati had burnt herself in the sacrified fire, and was consequently immortalized as Sati (the Truthful one). Lord Krishna's grandson Pradyumna was married to Usha, the daughter of King Banasur of Shonitpura (now known as Sarain near Rampur). It is said that at the end of the Satyg, the rishi Jamdgni was born here and tales about his son. Parashuram and wife Renuka are well-known in the region. Nirmand, the place where the saint Parashar performed Tapas and the origins of the Beas (Vija Sa Srofa) are located here. All in all, the entire area has a very long and rich historical past.