From : Wisdom Quarterly
Jainism: an extreme Buddhist school?
[Rajagriha] was King Bimbisara's capital, and it is equally important to the Jains, whose tradition parallels Buddhism to such a degree that some scholars suggest it is an offshoot or early school of Buddhism, distinct in adhering to severe austerities and nonharming (ahimsa). Indeed, the story of its founder has so many similarities to the Buddha's that one is hard pressed to imagine it all coincidental. (For instance, the Buddha hasn't always been popularly called "the Buddha." It's a title, and there have been many others applied to him, including "Great Hero," or Mahavira, which just happens to be the name of Jainism's founder). Rather, it's as if some early Buddhists were trying to reinvent the Dharma in more Brahminical/Hindu-friendly terms -- idolizing the yogic ideals of asceticism, complete renunciation, ahimsa, vegetarianism, equality (Jainism allegedly had nuns before Buddhism did) and utter detachment (non-possessiveness). It is telling that ancient Jain texts do not mention the Buddhists, whereas Buddhist texts do mention the Jains, referred to as Niganthas or "non-possessors."
Jainism is an examples of one of the extremes the Middle Path avoids -- self-mortification and completely abandoning the world. Refusal to be in the world while not of it means an uneasy coexistence, not coming to terms with the world. This is most evident in that orthodox (Digambara) Jain monks famously go about in the nude, refusing to possess even robes. And it is this uncompromising allegiance to extremes that has meant that unless one takes a religious studies class in college, one has probably never heard of Jainism outside of India.
However, an opposing view is that Jainism is in fact older than Buddhism. From A Comparative Study of Jainism and Buddhism,by Sital Prasad.
Jainism is older than Buddhism. Vardhaman Mahavira, the last Tirthankara of the Jainas was the contemporary of Gautama Buddha. The sects organized by the two leaders flourished for centuries together, before and after the Christian era. Although there were differences in the conduct of their monks in as much as the Jaina saints remained naked and the Buddhist monks wore cloths, there were closer resemblances between the two.
This book on Jaino-Buddhist religion places stress on the common factors on the religious life of the Jaina and Buddhists. On comparing the literature of both, the writer has come to the conclusion that coming in close association each sect has either borrowed from the other or both have derived material from common source. The work is an analytical account of Jainism and Buddhism. It is full of references. The author has exploited all the relevant material in discussing the subject. He has tried to show similarities between old Jainism and old Buddhism and prove that both were one and same at their base; that the old Buddhism was nothing but old Jainism and that Gautama Buddha must have preached the same philosophy that was preached by old Jainism. He has shown that the nature of Nirvana and its path as found in Buddhist Pali books are not different from the nature of Nirvana and its path as given in old Jaina works.