The North-East is a melting pot of ethnic and cultural diversity, includes religious diversity. According to the 2nd Administrative Reforms Commission report, the Northeast represents a state of stable anarchy where the rule of law and other institutions of governance are subverted directly or through collusive arrangements to serve the personal or partisan ends of the militants. North-east states like Nagaland, Manipur, Assam and Tripura had been witnessing insurgency since the 1950-60 period, but since 1990, the intensity of conflicts had started to decrease.

Distinct cultural identity is the primary cause of insurgency in the Northeastern states of India among others -

1. Assam: The major ethnic conflict in the state is the grievance against the perceived influx of ‘foreigners’ i.e. Bangladeshi, people with a language and culture substantially different from the Assamese. So, a movement started in Assam demanding the deportation of the illegal migrants led to the birth of militant outfits like the United Liberation Front of Assam (U.L.F.A.) in 1979, Bodo Liberation Tigers, National Democratic Front of Bodoland (N.D.F.B.), United People’s Democratic Solidarity (U.P.D.S.).
2. Tripura: Demographic profile of Tripura was altered in 1947 when mass migrations from the newly emerged East Pakistan converted it from a largely tribal area to one with a majority of Bengali-speaking plainsmen. This development sparked a violent backlash among the indigenous people and it lead to the emergence of one of the extremist outfits i.e. Tripura National Volunteers (TNV)
3. Manipur: One-fourth of Manipur (which is the valley), is home to more than seventy per cent of its population which predominantly consists of the culturally distinct Meitei community. The State was ruled by Meitei rulers. There was resentment among Meiteis about the merger of the State with the Union, which led to the Meitei insurgency in the 1960s.
4. Nagaland: The word "Naga" denotes a conglomeration of ethnic tribes living on the Himalayan Range in North East India and Burma. Naga people have been demanding (from the time of the British) that they should not be made a part of the union of India. Nagaland became the epicentre of this movement. Currently, the Naga people are demanding the creation of a “Greater Nagalim” to preserve their cultural identity.
5. Meghalaya: Time and again there are instances of violence against ‘outsiders’ particularly the Bengali-speaking linguistic minority. 

Other causes of insurgency in the North-eastern region of India -

1. Historical factors - As this region was loosely administered under British India, due to this it is not well integrated into the mainstream and as a result, the states in this region have resisted unification with India and had rather been raising the demand for a “separate nation.” Example: National Democratic Front of Bodoland (NDFB) for separate sovereign Bodoland, Bodo Liberation Tiger (BLT) for a separate “Bodo” state & NSCN for Greater Nagaland.
2. Geographical Factors -
1. Not well connected with the present Indian mainland, connected only through the chicken neck Siliguri Corridor
2. Difficult terrain and weak infrastructure facilitate insurgents involved in the conflict.
3. Porous international borders and easy availability of arms. e.g.China has provided some assistance to groups such as the N.S.C.N. in the 1980s.

All this has contributed to a sense of alienation that subsequently gave rise to a political culture of violent separatism.

1. Governance Factors - Lack of economic opportunities and governance deficit making it easier for people to feel alienated and left out and thus providing support for insurgency.  e.g. Apathy shown by the central government in the dreadful famine of 1959 led to resentment and the Mizo National Front (MNF) started a violent movement.
2. Economic Factors - On account of low industrial development in the region time and again we witness conflict in the region. e.g.
1. In Manipur, there was considerable tension among the tribes themselves over land and boundaries and thus violence erupted between Nagas and Kukis during the 1990s.
2. Disquiet in Arunachal Pradesh due to the settlement of relatively more enterprising Chakma refugees from Bangladesh and along with that growing income disparities and limited employment opportunities have the potential to threaten the peace in the state.
3. Political Factors - There is a struggle between different tribal group outfits to establish their political hegemony -
1. In the southern parts of the state of Manipur, some tribes have been waging violent struggles partly for local hegemony and partly for their enclave in the form of a Union Territory. 
2. In the case of Nagaland, disagreement over talks with the government led to the split of NSCN into the Issac-Muviah and Kaplan factions. NSCN (IM) agreed to a ceasefire in 1997. However, the Kaplan faction still resorts to violence.

          Thus, insurgency in the northeastern region is a multi-facet issue. So, to address this the government has also adopted a “multi-pronged” approach i.e. given special power to military forces under (AFSPA), peace talks with insurgent groups (e.g. framework agreement was signed in August 2015 with NSCN-IM), political autonomy under the 5th & 6th schedules, special provisions for certain states under article 371 (e.g. Nagaland, Assam, Manipur) and lastly to ensure inclusive development of this region Ministry of Development of North Eastern Region (DoNER) has been created.