Question

What were the reasons behind the decline of Buddhism and Jainism?

Answer 1

Reasons for decline of 
Jainism:
•Extreme ways of penance, far from comfort zones of practicality.
•Lifestyle centering non-violence, concept of Ahimsa seen too far.
•Lose of patronage beyond a phase
•Made no efforts to spread their religion, owing to the belief in non-compelling others
Budhism:
•Shift from language from Pali to Sanskrit ( Hinayana to Mahayana) ~ got distanced from masses.
•Corrupt practices amongst monastries with time.
•Attacks of Huna and Turk invaders
•Loss of Royal Patronage
•Hinduism reformed itself and revive.