You may wish to look into the surviving, vestigial manifestation, in the form of the guṭhī of Newar society in Kathmandu. There is a Wikipedia article on the subject https://en.wikipedia.org/wiki/Guthi

(though it's misspelled there with a dental instead of retroflex consonant). But I imagine that the literature on Newar sociology and anthropology with have more - perhaps some of the others on the list can help with bibliography in that area.

Matthew