Among the Meitei insurgent groups, United National Liberation Front (UNLF) is the oldest one. It was formed under the leadership of Areambam Samarendra Singh on November 24, 1964, to achieve independence and a socialist society. It established links with the Naga and the Mizo insurgents and contacts with Pakistan and China to garner support. A pan-Manipuri Youth League was formed in December 1968, which functioned as an overground body for UNLF. However, differences within UNLF regarding the strategies to be adopted surfaced at the same time. While Samarendra Singh sought to spread ideological consciousness before launching an armed struggle, the more radical leader Oinam Sudhir Kumar established a Revolutionary Government of Manipur (RGM).

In the seventies and eighties, UNLF concentrated mainly on recruitment of members. Unlike other insurgent groups, it did not resort to robberies and "tax" collection as it was more or less self-reliant. It set up a farm in Koodong, Chandel district. UNLF also established a school where children of nearby tribal villages were given education. Moreover, UNLF owned a printing press for its propaganda activity.

After maintaining a low profile for about two decades, in 1990, UNLF decided to launch an armed struggle for the "liberation" of Manipur from India. It formed an armed wing called Manipur People’s Army (MPA). The approximate strength of MPA is reported to be 300. MPA began its armed actions by killing five security forces personnel on December 15, 1991, in Lamdan, Churachandpur district.

On May 22, 1990, UNLF along with other insurgent groups operating in the Northeast – National Socialist Council of Nagaland-Khaplang (NSCN-K), United Liberation Front of Asom (ULFA) and the Kuki National Army (KNA), floated a pan-Mongoloid coalition called the Indo-Burma Revolutionary Front (IBRF) to wage a "united struggle for the independence of Indo-Burma".