William Charles Benett, Gazetteer of the Province of Oudh Vol-2 -- H. to M. (1877)
“ Nor can it be alleged that this is the final ra of the genitive transmitted in various ways, for we find the affix itself separate, both in Mathura and Oudh, airo as the name for old villages, whose origin is unknown, and from which many others have been settled. If these terminations cannot be derived from the Sanskrit, and if Tura- nian tribes, which must have passed through Northern India from Upper Asia to the Dekkan, do use the precise word for town, which is found as an affix in innumerable Oudh towns, surely the conclusion is irresistible that the affix was thenco derived. ”
