Harmony between the tribal and the non-tribal has been excellent for a long time despite large-scale migration of the non-tribal. But during the later half of 1970s, organised tribal militancy started spreading roots in the State. Strong feelings of social and economic deprivation & insecurity combined with communal feeling and ambition for political power deposited in the minds of a section of tribal youths. These feelings mixed with adventurism and aids from foreign agencies got stronger in the later part of '70s. As a result, the untoward ethnic riots took place in June 1980 when more than 1300 tribal and non-tribal got killed by each other & large-scale arson and damage of properties also took place.
First organized-armed tribal movement was known as SENKRAK which manifested itself in mid sixties in Manu, Chaumanu, Kanchanpur and Khowai areas. This movement was started as a reaction to settling down of non-tribal refugees in the Tribal Reserve Forest Areas. SENKRAK activists launched a large number of violent attacks on Government officials also. This movement was however, controlled in 1968.
TRIPURA NATIONAL VOLUNTEERS (TNV) / ATPLO :-
Mr. B.K. Hrangkhawal, a young tribal leader of 'Tripura Upajati Juba Samity', a regional party for the tribal, formed an underground organisation styled as "Tripura National Volunteers (TNV)" on 10th November, 1978 with a design to conduct insurgent activities in collaboration with the Mizo National Front (MNF) of Mizoram. There were wide spread communal riots in the State in June, 1980 when a large number of people from two ethnic communities lost their lives. Sri B.K. Hrangkhwal was arrested in June, 1980 and lodged in jail. On his release from jail in Dec, 1980, he announced dissolution of TNV.
But, some followers of TNV led by Mr. Binanda Jamatia formed another extremist group styled as "All Tripura People’s Liberation Organization (ATPLO) on 12th Dec, 1980 at Thangnan, Mayani Reserve Forest, Bangladesh. In 1981 Mr. Chuni Koloi broke away from ATPLO led by Binanda Jamatia. Mr. Jamatia arranged kidnapping of Mr. Hrangkhwal & his wife, Mrs. Linda Hrangkhwal from their house at Kamalacharra, under Ambassa Police Station on 13th Aug, 1982, suspecting his support to Chuni Koloi. Hrangkhwals were kept confined in Thangnan camp under guard.
On 3rd Sept, 1982 Chuni Koloi and his followers raided Manu Police Station and looted a huge number of arms and ammunitions. The faction led by Chuni Koloi, after becoming stronger than the faction led by Mr. Jamatia, attacked ATPLO Camp at Thangnan and rescued Mr. B.K. Hrangkhwal from captivity. Many ATPLO members surrendered to Chuni Koloi. On 10th Nov, 1982, TNV was revived with B.K. Hrangkhwal as its President. Binanda Jamatia and his supporters took shelter in South Tripura. Later, in response to a call of Mr. Nripen Chakrabarty, the then Chief Minister, Mr. Binanda Jamatia & his followers surrendered before the State Government on 23rd July, 1983. The ATPLO became defunct.
TNV activists continued their attacks with renewed vigour and intensity. Their attacks were directed to killing non-tribal and security personnel and looting of arms and ammunitions which continued till 1988. On 12-08-1988 a Tripartite Accord was signed by the Government of India, State Government of Tripura and the TNV. In all 447 TNV activists led by Mr. B.K. Hrangkhwal surrendered before the Government with arms and ammunitions.
TRIPURA RESURRECTION ARMY (TRA) :-
Mr. Dhananjoy Reang, who had been Vice-President of the TNV & President of the NLFT, formed TRA on 11th Feb, 1994 following an attack on him by a splinter group of NLFT in his hideout in CHT, Bangladesh on 10th July, 1993 as per direction of Bishwamohan Debbarma and Joshua Debbarma. However, Dhananjoy Reang could manage to escape with a quantity of arms & some of his followers. This outfit could not sustain itself for long and finally surrendered to the Government of Tripura on 5th Feb, 1997. Mr. Dhananjoy Reang and his followers have declared total dissolution of the gang.
OTHER GROUPS :-
A large number of small groups of extremists having link with either NLFT or ATTF came into existence and perished. Those having link with NLFT were - Tripura National Liberation Front (TNLF), Tripura Tribal Volunteer Force (TTVF), All Tripura Volunteer Force (ATVF), Social Democratic Front of Tripura (SDFT), Tripura Tribal Democratic Force (TTDF), All Tripura Volunteer Association (ATVA), Tripura Tribal Action Committee Force (TTACF), Tripura Humkurai Sepoy (THS), All Tripura Security Armed Force (ATSAF), Liberation of Tripura Tribal Force (LTTF), Tripura Regimental Force (TRF), All Tripura Bharat Suraksha Force (ATBSF), Tripura National Sengkrak Force (TNSF). The groups having association with ATTF were - Tripura Tribal Youth Force (TTYF), Tripura Liberation Organization (TLO), Tripura Young Rifle (TYR), Tripura Lion Force (TLF) and Tripura National Army (TNA). These groups were basically criminal gangs and do not exist at present. One group called Borok National Council of Tripura (BNCT) which came into existence in 1997 & were over ground collaborators of NLFT used to kidnap non-tribal and hand them over to the NLFT. The group was also involved in lifting of cattle of non-tribal residing in the interior areas.