Armed insurgency in Tripura dates from the 1970s, and arises from the ethnic conflict between the native tribal population and successive waves of Bengali immigrants from neighbouring Bangladesh. After partition in 1947, this former principality became part of India, and thousands of Hindu Bengalis arrived from Muslim East Pakistan. After East Pakistan became independent Bangladesh in 1971, there was another major influx of Bengali refugees, leaving Tripura’s 19 tribes as a demographic minority. The Tripura National Volunteers (TNV) were the first to take up arms against the tribes’ perceived economic and social marginalisation. After the TNV ended its decade-old struggle in 1988, the cause was taken up by the National Liberation Front of Tripura (NLFT), the All Tripura Tiger Force (ATTF) and myriad smaller groups. The insurgency’s aims included sovereignty for Tripura and the eviction of Bengalis. Militant Bengali groups formed in response. Violence has continued despite a 1993 peace agreement and a 2004 government deal with some guerrilla factions. However, casualties and attacks are much reduced.