Knutson, Jesse. The consolidation of literary registers in the world of the Senas and the beginning of its afterlife: Sanskrit and Bengali social poetics, 12th–14th century. PhD diss., University of Chicago, 2009. [PDF]
Some interesting insights here on the genesis of the Caryāpada, with reference to the period’s “song-poetry” of Baḍu Caṇḍīdās.