When people Worship as ordained by Vedas, simultaneously they also worshipped in the local language,mother tongue. The Bhakti Bhava is more compatible with one's mother tongue. Hence many Saints practicing Bhakti Yoga,left behind their experiences of Godhood in Local languages. These remain at the regional level and are practiced even today. Thus we have Bengal ,Assam,Odisha following the Bhakti Bhava practices from Bengali and Oriya primarily in the East,North East of India. In the West Marathi Bhava is in place.
It is said that Vedas follow Vishnu,while Vishnu Follows Tamil,alluding to the fact that,while the idol of Vishnu is in procession, those who chant Tamil Hymns from NalayiraDivya.Prabhabandha,precede the Idol,while Those who chant Vedas follow behind the Idol