Because it originated as an opposition to Hinduism, it was hated by Hindu priests. However, they were unable to stop it from growing and from achieving a great deal of philosophical growth as well, for 1400 years. This period of time caused Buddhism itself to go through many changes. In 800 AD, a very strong intellectual challenge to Buddhism was mounted by a Saivite priest who refined the philosophy of Advaita, with which he achieved great success in religious and philosophical discussions. These were considered very significant tests of relevance for winning royal favour. By this time, Buddhism had ceased to be a revolutionary, anti-establishment movement, and depended on royal patronage. There was a significant shift in favour of the revived Hinduism, and a decline in state sponsorship of Buddhism.
Buddhism still continued until the period 1000 AD to 1300 AD. However, from those years onwards, there were repeated attacks on north Indian kingdoms by Afghanistan- and Persia-based Turkish kingdoms, who gradually ground down the resistance of the Rajput kings who ruled north India then, and progressively established themselves in north India. These Turkish, Afghan and Persian conquerors slew Buddhist monks in large numbers, and destroyed their monasteries and their places of pilgrimage. From after this period, Buddhists merged more or less rapidly with the surrounding population of Hindus. Some parts that were Buddhist are thought to have converted in very large numbers to Islam.
It is not clear why Buddhism was so vulnerable to the challenge of Islam, and Hinduism was apparently less vulnerable.
Please stop being so vulgar and aggressive all the time. It is very unpleasant.
