Question

how did bhakti became very popular?

Answer 1

Bhakti Movement had its genesis in the South of India in the 6th century B.C..The Bhakti Movement gained momentum from the 12th centuries in the central western regions of India, then moved northward coming to an end roughly in the 17th century​.

In South India, the Nayanmars and Alwars were the noted saints of the Bhakti movement. They were the devotees of Shiva aqnd Vishnu respectively.The rulers that time built temples for the saints to strengthen the link between the Bhakti tradition and temple worship.