In the sixth century BC Buddhism emerged and took root in the subcontinent.
In the late Vedic age many people were unhappy with Hinduism, its strict rituals and caste system. They developed a new set of teachings known as the Upanishads, which provide an explanation of how people are born into different castes that it depends on their actions from a previous life, or karma. By 500 BC the doctrines of karma and reincarnation were generally accepted. However many, particularly of the lower castes, sought more change and room to actively participate in their religion. They found answers in Buddhism.
Buddha was born as a royal prince, Siddhartha, in 624 BC in a place called Lumbini (now part of present day Nepal). Prince Siddhartha led a sheltered life for most of his early years. But once he began to leave the palace, he saw sights of suffering, disease and old age. He was so disturbed that he left his royal life behind in search of answers. He searched for many years. While meditating under a Bodhi tree for several weeks he attained Enlightenment, where he realized the causes of suffering and the path out of it. He preached the Four Noble Truths and Eightfold Path which is to practice right speech, thought, intentions and actions. Part of this was the notion that people should be respected according to their actions and deeds rather than their caste. These teachings appealed to many and were quickly accepted throughout the northern part of the subcontinent.