Synopsis Unlike Islam and Christianity Hinduism is not a religion which took birth at a particular point of time due to the teachings of some human founder; its nature is eternal though ever-changing (pravahi sanatana). It is only in the case of some of its sects that one can talk of their emergence at a particular time doe to the teachings of some religious leader. The roots of Hinduism are embedded in our remote prehistoric past for which no written texts are available. Even their memory of it is now lost and only some of their remnants have been resuscitated by modern scholarship with the help of archeology and philology. The present monograph deals with the earliest phase of Hinduism beginning with the contribution of prehistoric people of India and the Indus Valley Civilization to her religious heritage along with a detailed picture of the vedic and Upanishadic religion which gradually gave way, though not wholly, to the Pauranika religion which is by and large still the dominant from of Hinduism. We fervently hope that this work, which includes and details the results of the latest researchers and discoveries, will be found useful by the learned scholars.