In the 5th Century B.C., both Buddhism and Jainism rose as spiritual orders that basically rebelled against Brahmanical Orthodoxy. Impregnated by the seeds of spiritual unrest, these twin offshoots yielded in the realm of history a harvest of new interpretations in religious broad-mindedness.
Both Gautama and Vardhamana who have come to be associated with the two cults as the paramount figureheads of their respective reform movements happened to be from the Kshatriya clan, who challenged the spiritual hegemony of the Brahmanas just as they refused to acknowledge the paramountcy of the Vedas. It was basically a clash of ideals between the governing and intellectual classes, each of whom brooked its own exclusivity in the social fabric of the society. Here it must be mentioned that neither Buddhism or Jainism were rigid schools of religious reform to the extent of attempting obliteration of Hinduism itself, in the sense that they never preached the abstinence of individual faith in the Hindu deities. Both existed as corollaries of the tenets enshrined in Hinduism and both alluded to a religious order that preached to the closest approximation, a chastity in words, thoughts and deeds as the means to salvation.
However, unlike Jainism which remained close to its Hinduistic origins in that it adhered to the rudiments of the caste system and ceremonial sanctity, Buddhism gradually was weaned away from the parent stock and thus, weakened its base in the country. While Jainism continues to flourish in its country of origin, spreading out of the Magadhan seat of imperial power to parts of North-West and to the Southern parts of India, Buddhism has been uprooted quite a bit and has gone on to flourish in South and South-East Asia. Several reasons have been cited for this. Even as many of the Buddhist doctrines came to be assimilated in the Hinduistic folds, the supremacy of the Brahamanic order that was challenged during the 5th and the 6th Centuries B.C., once again gained ascendancy during the age of the Guptas somewhere around the 3rd and the 4th centuries A.D., which mitigated the hold of Buddhism on the masses. Paradoxically, the neo-atheistic doctrines of Buddhism did not carry any level of conviction for the masses that was seeped in idolatory practices and sermons for centuries on end. Then of course, came the corruptible influences in the Buddhist monasteries and the religious order, followed by the horde of invasions which saw Buddhism lose much of its primal energy. The spirit of compassion and religious freedom thus, became a more potent antidote in far off lands that never required the Hinduistic crutch to flourish.
It must be admitted however, that both Buddhism and Jainism occupy a status of paramountcy in the religious orders that have flourished in India even though there is no definite period to delineate in history as either the Buddhist or the Jain period. Both are like the spiritual fountainheads that have attempted to create an outlet for human sufferings through the ever-flowing waters of purity and wisdom.