India is a country of heterogeneous ethnic and social groups which have their own languages and dialects. This broad linguistic regional identity formed the basis for the formation of Indian states. According to 1961 Census there were 1652 languages spoken by different sections of the Indian society. Of these 23 are spoken by 97 per cent of the country's population. Eighteen languages, as mentioned in the Eighth Schedule of the Constitution, are spoken by 91 per cent of the people of the country. Indian languages mainly belong to following four linguistic families.
1. Indo-European Family (Arya)-these languages are spoken by a sizeable population of the country which is confined to the Indo-Ganga plains. These are sub-divided into two main branches: Dardic and Indo-Aryan. Former includes Dardi, Shina, Kohistani and Kashmiri while the latter is divided into north-western (Lhanda, Kachchi, Sindhi), southern (Marathi, Konkani), eastern (Oriya, Bihari, Bengali, Assamese), east-central (Avadhi, Baghaili, Chhattisgarhi), central (Western Hindi, Punjabi, Rajasthani, Gujarati), and northern (Nepali, and Pahari) groups.
2. Hindi is the principal language of the Indo- European family which is spoken by 337.27 million (39.85 per cent) people of the country. It is mainly spoken in Uttar Pradesh, Madhya Pradesh, Bihar, Rajasthan, Haryana, Himachal Pradesh and Delhi. Urdu is closely akin to Hindi and is popular in Uttar Pradesh, Bihar, Delhi, Andhra Pradesh and Karnataka. Marathi is the most important language of Maharashtra in South India. Similarly Bengali, Oriya and Assamese represent the eastern group in the states of West Bengal, Orissa and Assam respectively and Nicobari). These are mainly spoken by the tribal groups in the Khasi and Jaintia hills of Meghalaya, Nicobar Islands, Santhal Pargana, Mayurbhanj, Ranchi, East Nimar, Betul and Baudh Khondmals.
3. Sino-Tibetan Family (Kirata)-this family consists of three main branches: (a) Tibet Himalayan (Tibetan, Balti, Ladakhi, Lahuli, Kanauri, Lepcha), (b) North Assam (Aka, Dafla, Abor, Miri, Mishmi, Mishing), and (c) Assam-Myanmari (Bodo or Boro, Naga, Kachin, Kukichin and Myanmar). These languages are mainly spoken by the tribal groups of the North-East and of the Himalayan and sub-Himalayan region of the North and North-West. The speakers of the Tibet Himalayan branch are concentrated in Ladakh, parts of Himachal Pradesh and Sikkim. Assam-Myanmari branch spreads along the Indo-Myanmar border. Among these, Naga dialects are spoken in Nagaland, Lushai in Mizo hills, Garo in Garo hills and Meitei in Manipur.
On the basis of the principal languages India may be divided into 12 linguistic regions. These include Kashmiri, Punjabi, Hindi, Bengali, Assamese, Oriya, Gujarati, Marathi, Kannada, Telugu, Tamil, and Malayalam regions. These very well correspond with the states of the Indian Union. Despite this linguistic diversity Sanskrit during ancient days, Persian during the medieval period and English during the modern period act as link languages helping the cause of national integration and unity.