It seems there was another religion before Hinduism, life was mostly simple, tribal and nomadic...The earliest evidence for elements of Hinduism date back to the late Neolithic to the early Harappan period (9500%u20132600BC) ... of course at that point of time no one knew what religion.. it developed through social, cultural and traditional practices and knowledge acquired over thousands of years, and so it lies as diverse as its today. Also, you dont have to get officially stamped as an Hindu, you just need to believe you are so to be one, unlike any other younger religions where you would have to have religious baptism etc. Philosophically thinking, even today, every person is born a Hindu. :)
