Question

major reasons behind the bhakti and sufi movements​

Answer 1

The medieval period in India saw the rise and growth of the Sufi movement and the Bhakti movement. The two movements brought a new form of religious expression amongst Muslims and Hindus. ... The Bhakti saints transformed Hinduism by introducing devotion or bhakti as the means to attain God

Answer 2

Bhakti is a devotion to a deity . The idea of  bhakti was given in bhagavadgita  

Sufi saints were Muslim mystics.They believed that the heart can be trained to look at the world in a different way.some Sufi saints made silsilas which were the sufi saints who followed slightly different method of ritual practice