The 1991 Census of India lists 1,576 mother tongues with separate grammatical structures and 1,796 speech varieties classified as "other mother tongues"
The 2001 Census of India lists a total of 122 languages and 234 mother tongues with over 10,000 speakers. Of these 122 languages, 22 have been included in the Eighth Schedule of the Constitution.
For more information regarding Census results on languages from the years 1971, 1981, 1991 and 2001 please refer to the Census of India website
Note: The 1971, 1981 and 1991 Census results do not disclose the data of languages with less than 10,000 speakers