These groups, _janas_, Latin gens, are subdivided into _vicas_, Latin vicus, and these, again, into _gr[=a]mas_.

The names, however, are not employed with strictness, and _jana_, etymologically gens but politically tribus, sometimes is used as a synonym of _gr[=a]ma_.[4] Of the ten books of the Rig-Veda seven are ascribed to various priestly families.

In the main, these books are rituals of song as inculcated for the same rites by different family priests and their descendants.

Besides these there are books which are ascribed to no family, and consist, in part, of more general material.

The distinction of priestly family-books was one, possibly, coextensive with political demarcation.