The All Adivasi National Liberation Army, which the Assam police suspected of carrying out Thursday's attack that rocked the Dibrugarh-Guwahati-New Delhi Rajdhani Express, was floated by a section of frustrated tea tribe (Adivasi) youth in 2005.
The militant group has a strong bastion in the forest areas along the border areas of Golaghat and Karbi Anglong district of Assam. It has recently spread its tentacles to the tea belt area of the Udalguri district of North Assam.
A senior Assam police official said the AANLA was floated by a desperate band of Adivasi youths. The outfit was formed with the help of bigger insurgents groups including the Naga rebel group, National Socialist Council of Nagaland-IM and the United Liberation Front of Asom.
The bigger groups were suspected to be providing arms and training to the AANLA cadres. The bigger groups utilised the AANLA to launch extortion drives in the tea belt of Golaghat district and Karbi Anglong.
Of late, the ULFA became cool towards the AANLA and accused the latter of trying to create a division between the tea tribe community and the other ethnic groups in the state in the wake of the last incident of violence involving Adivasi agitators in Beltola area of Guwahati.
A few members of the AANLA recently surrendered before the police, while seven others, including the deputy commander in chief of the group, were arrested by the police in Guwahati on December 10.
The arrested AANLA leader confessed to sponsoring higher education of a few Adivasi students in Guwahati so that they could be later lured into the ranks of the outfit.
The AANLA is also suspected to have triggered the street violence at Beltola area in Guwahati on November 24.
The police suspect that it was the AANLA cadres in the Adivasi rally who first started the violence by attacking private property and vehicles on the road.
