All the above-mentioned comments made by language experts express the fact that Mother Tongue is a very important aspect of human life as well as society. According to U.N.O the indigenous people who live in 90 different countries of the world, probably carry 5000 different culture and 4000 different languages. But now these diversified languages are dying day by day just like the animals die in the forest due to lack of proper food, water and favorable environment. This extinction of language is not only evident in India but also visible in other developed countries like Brazil, Australia, Japan, Malayasia etc.
Language plays a significant role in human life. Language is not only a medium of communication or education, but it also acts as a shield of individual identity of a community. Indigenous languages bear invaluable heritage and are embodiment of indigenous ancestors and it is very important to preserve their language for the preservation of their culture. Nearly 67000 languages are spoken in the world and half of them are indigenous languages. The language experts opine that due to the pressure and impact of developed languages of cities and towns each week an underdeveloped indigenous language becomes extinct. If this extinction of language continues for long, then in the 21 st century probably 50% to 90% of indigenous languages will disappear from the world.  
Along with language, it has also become inevitable to preserve the age-old tradition, culture and identity. By keeping this in mind U N General Assembly was created in 2016 and 2019 was declared an International Year of Indigenous Languages. And UNESCO started to work on people’s awareness about their languages. These programs actually helped them to revive their language, literature and culture. They organized various seminars and conferences at District, State and National levels to preserve these endangered and underdeveloped languages. The United Nations has shown the path to promote such endangered languages of indigenous peoples in different countries. But in our country the promotion and upbringing of indigenous languages, literature and culture always remained neglected due to the politics of Centre and State, vote bank policy and establishment of the academics.
According to heredity and genealogy of Indian language and dialects, Mother tongue/language is divided into four categories.
1. Aryan languages
2. Austric languages
3. Bhot-Burmese / Sino-Tibetan languages 
4. Dravidian languages
(1)    Aryan Languages of India
I)     Sanskrit
II)     Bengali,Rajbangshi/Kamtapuri        
III)     Hindi, Rajasthani, Marwari, Bhojpuri, Maithili, Awadhi, Maghi, Kangri, 
        Kumau, Madhesi etc.
IV)       Nepali- Rai, Limbu, Chhetri, Magar, Tamang, Damai, Kami, Sarki, Gurung,  
        Sherpa, Sunar etc. 
V)   Sadri-Sadani/Nagpuri- Lohra, Mahli, Chamar, Ghasi, Turi, ChikBaraik, 
        Kumhar etc.
VI)    Asmiya
VII)  Udiya
VIII) Gujrati
IX)    Marathi
X)     Panjabi
(2)    Austric Languages – Santhali, Mundari, Kora, Kurmi, Khariya, Ho, 
    Birhor, Bhumij, Sabar, Lodha, Khariya, Sabar etc.
(3)    Bhot-Burmese/Sino Tibetan Languages –  Mech/Boro(Bodo), Rava, Garo, 
    Lepcha, Bhutiya, Dukpa, Dhimal, Toto, Laddaki, Tibetan & Sikimi etc.
(4)    Dravidian Language family –  Kurukh(Kurux) / Oraon, Koya, Kisan, Khond, 
    Malto, Tamil, Telegu, Malyalam, & Kannad / Kanadi. 
Austric, Bhot-Burmes and Dravid languages are considered as indigenous or 
    Adivasi languages.
In India only 22 languages out of 114 prominent languages are included in 8th schedule of Indian Constitution. Total 15 languages of India which have their own scripts are imprinted in the Indian currency notes. Santhali and Bodo are the two new languages recently included in the 8 th schedule of Indian Constitution. 
In the census of 1961 it was recorded that there were 1652 mother languages, but in 2001 the number was decreased to 122. Now the question arises that, where these 1530 languages have gone in the last 40 years? The possible reason behind the extinction of these languages is government’s weak language policy. It has been mentioned in the government policy that the language communities which have ten thousand speakers will be given recognition and other languages will not be included in the list. Thus, it has become imperative that the languages which are left without government recognition die a natural death.  
The Aryan languages i.e Bengali, Hindi and Nepali are basically spoken and written in six Districts of West Bengal like Maldah, Uttar Dinajpur, Darjeeling, Jalpaiguri, Coochbehar, and Alipurduar but the impact of Bengali is much more evident in Maldah, Uttardinajpur and Coochbehar districts. In Coochbehar most of the people speak in Rajbangshi or Kamtapuri language. In Tarai region of Darjeeling and Dooars of Alipurduar, Jalpaiguri, Aryan languages such as Bengali, Hindi along with Nepali and Sadri are spoken by the majority of people.
Nepali language is used as a link language to communicate between the Bhot-Burmese and Adivasi people in Darjeeling hill areas and Tarai region. Nepali is a very developed language and it is taught in various institutions from school to university level. Newari, Magar, Limbu, Tamang, Sherpa are the dialects of Nepali. As Nepali is used as a medium of education, many Tribal communities such as Garo, Lepcha, Bhutiya, Dukpa, Dhimal, Toto etc are forced to accept this language and it results in the inclusion of many Nepali words in their usual tongue. Nepali language does not have its own script. It uses Devnagri script.
In a similar way the Dravidian  language such as Oraon, Munda, Khariya, Bhumij etc. use the Aryan language Sadri / Nagpuri as a medium of communication between two other communities. Sadri is used not as a mother language but as a link language to communicate. 
It is mostly used in Terai-Dooars region.  Here Bengali, Hindi and Nepali are also used in the same way but Sadri is specially used as a link language between different Jharkhandi Adivasis. There are several communities who lost their mother language and accepted Sadri as their second mother tongue. In this way due to the impact of Sadri language Dravidian languages of Terai and Dooars are forced to extinction. This ultimately leads to the death of a particular community.
The language experts believe that Sadri language belongs to Aryan language family but the people who speak in this language claim themselves as indigenous or adivasi. So the question arises - why would a tribal speak in an Aryan language? Well, there can be these possible reasons for keeping Sadri in  the Aryan language family.
This language is possibly created by the mixture of many Aryan languages such as – Hindi, Bengali, Rajbangshi, Bhojpuri, Asamiya, Nepali, Magdhi, Awadhi, Maithili, Odiya and Rajasthani etc. So, this language is not considered as a Tribal language i.e Santhali, Mundari, Ho, Khariya, Kurukh are self dependent languages and different from Aryan languages.
The Sadans (Sadri speaking people) who claim themselves as Adivasis, are of different communities but interestingly all of them speak in an Aryan language; they also claim Sadri as their mother tongue. How can a single language be the mother tongue of many different communities? There can be two possible reasons :–
(1) Perhaps the Sadan communities such as Lohra, Mahli, Turi, Khasi, Kumhar, Chikbaraik etc. had their own separate mother language in the past. But due to some unavoidable reasons,  they fail to preserve their mother language or may be due to the influence of other impactful Aryan languages they were forced to abandon their own languages. And ultimately their languages became extinct. In the present times Oraon, Munda, Khariya communities have started to abandon their own mother tongue and started to speak in Hindi, Bengali, English, Sadri or other mainstream languages in their family. It will ultimately lead to the extinction of their own languages.
(2) May be the Sadan communities had same ancestors in the past. But as they got acquainted with Aryans and were influenced by their Varna System/Caste System they might have divided themselves according to their profession. For example, the people who made things out of iron were known as Lohra. Similarly, the people who made clay pots were known as Kumhar ; the people who weaved clothes were known as Chikbaraik, the people who made things out of animal skin were known as Chamar. In this way, they divided themselves in different communities but their language remains the same. The Aryans considered the profession of Sadane as low class and kept them in the Sudra category of the Varna System (Caste System). As a result, other Dravidian  speaking people started to treat them as untouchables. This tradition was there among Austric & Dravidan language speaking people for at least 60 -70 decades. But with the expansion of education among the Adivasi communities, this tradition disappeared from their culture. A proper anthropological and genealogical investigation is much needed to know the accurate factual truth about Sadan people as well as Sadri or Nagpuri language.  
There are certain Adivasi / Tribal languages which are greatly endangered at this moment. Here I will try to shed light on these endangered adivasi languages –
TOTO – Totos are one of the smallest primitive Tribes of India. Their mother tongue is Toto but the medium of education is Bengali. The insertion of Nepali, Bengali and Hindi words in the Toto language is very much evident.  This language is becoming endangered as it is not used as a medium of education and it’s also greatly influenced by Bengali and Nepali.
DHIMAL: Dhimal is also a small primitive Tribe, just like Toto, their language is called Dhimal, but it does not have any script. They are using Bengali script to create literature in their mother tongue. Their Dhimali identiy is gradually destroyed by their close contact and acquaintance with Nepali and Rajbangshi community. They are on the verge of losing their identity.
DUKPA: They belong to Mangolian tribe. Their language is called “Le-Ke”. Tibetan people address their language as “Lohke” which is connected with Tibetan language. They do not have script. They use Tibetan script to write. This “Le-Ke” or “Lohke” language of Dukpa is greatly endangered due to dominance and influence of Nepali language.
RAVA: Rava/Rabha belongs to Bhot-Burmes/Sino Tibetan language group. Their language is known as “Kocha Kraw”. They do not have their own script. They are using Bengali script to write literature and their medium of education is Bengali. The consciousness of the Rabhas about their language helps them to keep their language alive.
GARO: Garo also belongs to Bhot-Burmes language group. The name of their language is “A-chik-Kroshik”. They do not have their own script. Basically they use Roman script but they are far away from creating literature.
MUNDARI: Mundari is a tribal language of Munda people and it belongs to Austric language family. In present times Munda people speak in Sadri, Hindi Bengali etc. and they are constantly abandoning their mother language. So this language is also endangered.
KHARIYA: This language belongs to Austric language family. It does not have its own script. Khariyas of North Bengal usually speak in Sadri at their home neglecting their own language. If the situation remains same then the language is going to be extinct from North Bengal in next 25-30 years.
MALPAHARIYA: In the Tea Gardens of North Bengal, there are people who have close contact with Dravidian language family. They live all over Bengal. Their language is called Malto which is a part of Kurukh.  They don’t have script. Most of the Malpahariyas speak in Hindi and Sadri languages, abandoning their mother tongue Malto. The Malto language is almost dead in Terai-Dooars. Modern youths do not speak in Malto.
LEPCHA: Lepcha is one of the oldest and rich languages. It belongs to Sino-Tibetan language family. It has its own script. The Lepchas basically live in Tea Gardens and villages of Sikkim and Darjeeling and speak in their own mother tongue. The infiltration of Nepali is very much visible in the language. They can also speak in Hindi.
SERPA: Serpas are Tibatan tribe. They basically live in the hill areas of Darjeeling. They hardly live in plain areas. They have their own mother tongue but the influence of Nepali is very much visible in this language.
RAI and LIMBU: There are many similarities found between Rai and Limbu community. Rai/Limbu has their own mother tongue but the influence of Nepali is very much evident in their language.
NEWARI: “Newari” belongs to Bhot-Burmese language family. The Newars live in three sub-divisions of Darjeeling district like- Kalimpong, Kurseong & Darjeeling. Their language is called Newari but they are generally considered as Nepali speaking people.
TAMANG: Tamang belongs to Bhot-Burmese language family. Their language is different from Nepali Language,  but it has some similarities with Tibetan language. Tamangs have their own script which is currently known as  “Tamik”. Their literary creation is available in Tamik as well as Devnagri script.
MECH/BODO (BORO): Bodo language belongs to Bhot-Burmese group. This language is very rich in itself but it does not have any script. Due to lack of script they usually write in Bengali or Devnagri script. A large number of Bengali and Assamiya words already infiltrated this language. In Assam this language is taught from primary School to university level. This is already included in the 8th Schedule of Indian Constitution. But it still remains neglected in West Bengal.
SANTHALI: Santhals live in almost every district of West Bengal. According to the number of tribal population Santhal people are largest in number. Their language is known as “ SANTHALI” and they have their own script,  called “ OLCHIKI”, which is very developed script. Their language also included in the 8th Schedule of Indian Constitution. The language is taught in primary schools as well as in universities of West Bengal and Jharkhand. But in few districts of North Bengal i.e. Coochbehar, Jalpaiguri, Alipurduar and Darjeeling there is not any facility of learning this language in school and colleges. Apart from 'Olchiki' Santhals also use Bengali, Devnagri and Roman scripts in their writing. Santhali literature is rich and well developed.
KURUKH/KURUX: The Oraon people address themselves as Kurukh. They belong to Kurukh/Oraon tribe and their language is called “KURUKH”. They address themselves as Oraon in front of others (other caste/community), while they call themselves as Kurukh/Kurkhar in front of their own people. The caste of this tribe is same but they have two names “Oraon” and “Kurukh”. So the question arises, how did they get two names? Here I will try to find out the possibilities.
KURUKH WORD: The language experts express different opinions regarding the derivation of this word --- 
i)     According to E.T.Dalton, the word Kurukh is derived from ‘Konkya’.
ii)     Language experts opines that the Dravid speaking people were known as ‘Korakh’ which later became as ‘Kurukh’.
iii)     In Drahuyi-speaking people (speakers) were known as ‘Korak’, ’Karok’ or ‘Kuruk’. It is believed that it eventually turned into ‘Kurukh’.
iv)     Dr Prakash Chandra Oraon thinks that Kurukh is derived from ’Korkoi’, ’Karush’ or  ‘Kurukshetra’. 
The speakers in Drahui language were known as ‘Kurukh’. This logic seems more applicable but if we look at the folklore of Kurukh /Oraon, it becomes clearer. 
At the dawn of civilization when the human lived at caves, they had to face many natural calamities, like flood, draught, storm, snowfall, earthquake, forest fire etc. The primitive people used to eat fruits, vegetables and raw meats. Sometimes due to forest fire the fruits, green vegetables and wild animals got burned. When the primitive people tasted burned foods, they found it very tasty. So they themselves started to burn or bake their food items. 
 In Kurukh language, the process of roasting anything in the burning fire is called as ‘Kurna’. The people who ate food by roasting it in fire were known as ‘Kurumukhu’ or ‘Kurukharu’. There is slight difference between  ‘Mokhna/Moxna’ or ‘Kharna/Xarna’ but the meaning is same, ‘eating’. The Mokhna verb is used to refer eating small foods, on the other hand ‘Kharna’ verb is used for eating big foods with the help of teeth (chewing, biting food in the mouth with teeth).
In the primitive age when people just started to use languages, the Kurukh ancestors address the people as ‘ Kurukharu/Kuruxaru’ who used to eat food, grain or meat by roasting it in fire. In this way the word “Kurukh /Kurux” derived i.e.- “ En kurukharu” means- I eat food by roasting it in the fire. Similarly – “Neen kurukharu” = You are roasting eater, “Aas/Aad kurukharu”= He/She is roasting eater, “Em Kurukharu” = We all are roasting eater and this way this term ‘Kurukharu’ / roasting eater becomes Kurukh or Kurux.
ORAON WORD: There are various debates regarding the genesis or derivation of the word ' ORAON ' such as ---
i)     Jagadish Trigunayet says that, according to Mundari folktales the term ‘Oraon’ may be a derived from ‘ uroAnge’ ( who digs till morning), ‘Hoorang’ ( who throws).
ii)     According to E.T.Dalton, 'Oraon' is derived from “Udan” or “ Uran” which means flying people. He also opines that ‘Oraon’ is derived from “ O..Rawan ”.
iii)     Sarat Ch. Roy opines that as they (Oraons) were born out of the chest of 
“ Tapaswi ” so they were addressed as “ Oraon “.
iv)     Dr Diwakar Minj expressed that they were born out of “ Munik’s Ur “( Munir’s Chest), so they are known as ‘Oraon’.
v)     Dr Prakash Ch. believes that the word ‘Oraon’ is derived from the chanting of the word “ O Ram… O Ram..” .
vi)     According to social activist Mangru Oraon, the word “Oraon” is derived from “         “ O Ramph” ( Light or ray of the sun).

It becomes very clear by these above mentioned opinions that there is a lack of proper and accurate information about the genesis or derivation of the word “Oraon”. These opinions are just hypothesizes which do not bear any resemblance to Oraon culture and language. These opinions are full of doubt.
In pre-vedic age Oraon people were known as ‘Kurkhar” but in post-Vedic age the Aryan Hrishi-Munies addressed them as “ Oraon/Uraon”. So the name ‘Oraon’ is given by the Aryans. The Kurukh ancestors have been observing the “Dandakattna, Bhelwa phari or Bhagkatti” pooja tradition from the pre-Vedic ages by following the ritual of Sarna religion. They used to pronounce some mantras during the observance of this tradition which was known as “Gurumna or Gurmana”. There is a particular way of ‘Gurmana’( mantra chanting) in which one has to close his/her eyes and mouth, concentrate on Dharmes ( the supreme God) and then he/she will pronounce the sound,  three times, like---- “Mmm…Amm…Humm…Umm… or Oumm…” through his nostrils. This is known as  'Rab' (sound) in Aryan language. So, people who pronounce the sounds of  “mmm…amm..humm..umm..or oumm..” later addressed by the Aryans as –"Uo-Rab", "Umm-Rab." “ Humm..Rab, Umm…rab, 'Ou-Rab'. This word later becomes  “ Uraon or Oraon”. This theory seems more promising as it resembles Kurukh/Oraon culture and language. It also seems that “Um or Om” sound is derived into Aryan culture from the Oraon/Kurukh language. It is important to notice that Kurukh word represent both the caste and language of Kurukh people, while ' Oraon ' only represents their caste not language.
GEOGRAPHICAL  AREA : Kurukh is a tribal language. The Kurukh speaking people live in Bihar,Jharkhand, Madhya Pradesh,  Chhattisgarh, Orissa, Maharashtra, Gujrat, Himachal Pradesh, Assam, Meghalaya, Arunachal Pradesh, Manipur,  Tripura and West Bengal. Apart from these, they also live in different countries outside India like Bangladesh,  Bhutan, Mauritius and Terai region of Nepal. In West Bengal the Oraon basically live in the district of Birbhum,  Nadia, Murshidabad, Uttar Dinajpur, Dakshin 24 Parganas, Purulia, Medinipur, Burdwan, Hooghly, and Sunderban regions. The Oraons are there in most of these districts of North Bengal, but in the Terai region of Darjeeling and Dooars of Alipurduar and Jalpaiguri. Their number is comparatively more. According to 1991 census the number of Kurukh speaking Oraons in Jalpaiguri District was 1, 59,616.
THE GENEALOGY OF THE LANGUAGE: Kurukh/Kurux belongs to Dravidian family of language,  same as Tamil,Telugu, Malayalam ,Kannada, Malto and Brahui and is the mother tongue of Oraons. Kannada, Tamil and Telugu are old languages of India.
Kurukh has its own grammar, syntax and vocabulary. The alphabetical Script of Kurukh is known as “JILONG SIKI”. This language is taught in the primary schools of Jharkhand, Orissa and Chhattisgarh. And it’s also taught at university level in Jharkhand. In Jharkhand Kurukh is officially the second language.
The Government of Nepal has recognized Kurukh as an official language and is taking steps to publish books and magazines in it. Monthly and Bi-monthly magazines are being published in Nepal. 
On the eve of 21 st February 2017, on the International Mother Language Day, the Chief Minister of West Bengal recognized Kurukh, Kamtapuri and Rajbangshi as official languages (Outlook-Kolkata ).  The West Bengal Government gave official status to KURUKH language, listed as an endangered language by UNESCO, to mark International Mother Language Day which is observed to mark the language movement in the East Pakistan in 1952. Announcing this at a function to celebrate the day, State Chief Minister Mamata Banarjee said that official recognition would also be given to Rajbangshi/Kamtapuri language spoken in different parts of North Bengal. She said that around 16 lakh Oraon people spoke Kurukh language and it had been identified as a vulnerable language in the UNESCO’s list of endangered languages. This historic decision of the Chief Minister caused much jubilation in the Rajbangshi and the Oraon community. The Gazette Notification was released a few days after and it was a huge step forward in the right direction. The West Bengal Adivasi Development and Cultural Board constituted the “ Kurukh Bhasa Sahitya Academi “ and the sub-committee was formed on 18 th March 2018. In this 15 member sub-committee, one member from CRI (Cultural Research Institute) and two faculty members from university should be included but it has not been implemented yet. 
The regulations pertaining to the introduction of teaching in Kurukh in West Bengal are not clearly out-lined. The Academy has not received proper instructions from the Government Bodies.  Kurukh Bhasa Study Centre, Kurukh Teachers Training Program, Kurukh Education Council, Kurukh Textbook and Syllabus Committee should have been constituted by now and steps regarding the implementation of preliminary education in Kurukh should have been taken by now. But our State Government is silent and the members of the Academy are sitting idle.
It has been three years since Kurukh was recognized as Official Language but none of the steps have been taken. If a language has to flourish, it has to be introduced in school curriculum but no such steps have been taken.  Kurukh Bhasa activists are silent and idle too. Nobody knows what the future holds for this language, but it is expected that the government would take necessary and meaningful steps for the  growth of this language.
Reason behind the crisis and the ways of rejuvenating the language:
According to the report of The Times of India and Hindustan Times, nine tribal languages of North Bengal are in deep crisis, these are – Hajong, Tharu, Jalda, Koya, Dhuliya, Rautiya, Sabar, Asur and Magar. The “Tundu” language has been totally extinct. There are specific reasons behind the extinction of each language.
1) The death of speakers, the loss of lives due to unavoidable natural calamities such as wildfire, deluge, landslide,  movement of glaciers, oceanic typhoons and other such malaise. Such devastation causes huge setbacks to speech community. Some speakers knowingly ignore and neglect their own language, these amount to the cold blooded murder of the linguistic communities.
2) The arrival of other linguistic communities , the failure of any language to position themselves as connecting language, the absence of recognition, all these factors cause the marginalization. These cause the speakers to treat their language as unimportant. They are forced to take the refuge of the dominant languages that are taught in school, colleges and universities. They start perceiving Bengali, Hindi and English as more useful than their mother language. As a result they start shifting towards other languages. This is what we refer to as “language shift.”
All the tribal communities of North Bengal, especially in Terai and Dooars have their own mother languages. But they are forced to complete their education in Hindi, Bengali, Nepali or English medium school. Student is obliged to choose one of these four mediums, whether he is capable of understanding the language or not. He is compelled to learn. This makes him psychologically servile to an unknown alien language. Education should always be imparted through mother language. Both the speaker and the apathy of the government are responsible for the extinction of any language. Language is identity for the tribal and communities. Language disappears society/community vanishes. People's the Linguistic Survey of India has recommended language documentation and language revitalization to stop this.
Language Documentation: This includes the proper archivization of grammar, syntax, oral literature, folk literature and folk tales of a particular linguistic community. 
Re-vitalization: This includes informing the linguistic community about the heritage, tradition and history of their language. This requires the participation of the members of a particular linguistic community. This helps them in realizing the importance of their customs, traditions and life and death rituals. All of these could be achieved by the effective implementation of linguistic policies, curriculum and organization of meetings and seminars.
It is important that they learn about their language, custom, traditions and beliefs of their ancestors. This aim could only be achieved through the introduction of mother language. All these socio-cultural documents will greatly help the future generation to research, investigate and interpret their collective past.