The language was first described and classified by indologist Kamil Zvelebil, who in 1955 showed that the Irula language is an independent Southern Dravidian language akin to Tamil, particularly Old Tamil, with some Kannada-like features. Before that, it was traditionally denied or put to doubt, and Irula was described as a crude or corrupt mixture of Tamil and Kannada.
According to a tentative hypothesis by Kamil Zvelebil, a pre-Dravidian Melanid population that forms the bulk of the Irulas anthropologically, adopted (or perhaps was forced to adopt) an ancient pre- or proto-Tamil dialect, which was superimposed almost totally on their native (pre-Dravidian) speech. This new speech-form then became the basis of the Irula language, which must have subsequently been in close contact with (and hence influenced by) the other tribal languages of the Nilgiri area as well as with the large surrounding languages such as Kannada, Tamil and Malayalam.
^Perialwar (1979). Ethnologue (Irula language at Ethnologue (17th ed., 2013)) sets the number at more than 200,000 speakers. In reality, other social groups from South India bear the name of Irula but aren't necessarily related to the population of Nilgiri.
^Nordhoff, Sebastian; Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, eds. (2013). "Irula". Glottolog 2.2. Leipzig: Max Planck Institute for Evolutionary Anthropology.