The 1960s and ’70s: Separation of Nagaland, Meghalaya, NEFA, and Mizoram

Between the early 1960s and the early 1970s, Assam lost much of its territory to new states that emerged from within its borders. In 1963 the Naga Hills district became the 16th state of India under the name of Nagaland. Part of Tuensang, a former territory of the North East Frontier Agency, was also added to Nagaland. In 1970, in response to the demands of the tribal peoples of the Meghalaya Plateau, the districts embracing the Khasi Hills, Jaintia Hills, and Garo Hills were formed into an autonomous state within Assam, and in 1972 it became a separate state under the name of Meghalaya. Also in 1972 Arunachal Pradesh (the North East Frontier Agency) and Mizoram (from the Mizo Hills in the south) were separated from Assam as union territories; both became states in 1986.

1979–85: the Assam Agitation and the Assam Accord

Communal tensions and violence remained a problem in Assam even after the four ethnic-based states were created. In the early 1980s resentment among the Assamese against “foreigners”—mostly immigrants from Bangladesh—led to widespread violence and considerable loss of life.

Migration of Muslim peasants from what was East Bengal (which became East Pakistan and then Bangladesh; to learn more, see history of Bangladesh), to the Brahmaputra valley had happened over centuries. British colonial policies focused on increased agricultural productivity, and revenue had influenced the migration in part. In the first half of the 19th century, following the Treaty of Yandabo, Bengali peasants were driven away to the fertile lands of neighboring Assam by “push factors” such as famines, the permanent settlement system, and other exploitative policies introduced by the British in Bengal. British policies also encouraged settlers from East Bengal to move to the fallow lands and the wastelands (chars). With the development of tea plantations and the establishment of railway lines in the second half of the 19th century, more laborers migrated into the region, and a high number of these migrants were from eastern Bengal. With the partition of India (1947), the 1965 India-Pakistan War, and the Bangladesh Liberation War (1971), millions of refugees from the region migrated to northeastern India, particularly Assam and Tripura. This led to an “us versus them” feeling between the indigenous Assamese people (khilonjia) and the migrants, termed “foreigners” and “illegal immigrants,” among others.

Driven mostly by concerns about cultural and linguistic identity, changing demographics, and political power, the All Assam Students’ Union (AASU), which was led by Prafulla Kumar Mahanta, spearheaded the anti-foreigner campaigns that came to be known as the Assam Agitation, or the Assam Movement. This was a period of popular agitation and communal violence in the state, and president’s rule was imposed to maintain law and order thrice during the years of the agitation. The Nellie Massacre on February 18, 1983, in the backdrop of state assembly elections and disagreements over the inclusion of “foreigners” in the electoral rolls, was one of the largest incidents of violence in the country since independence. Hundreds of Bengali-speaking villagers were reportedly attacked by neighboring villagers, ending in the killing of more than 1,800 people (accounts vary, with some reporting 5,000 deaths). AASU and allied groups called the central government’s attention to the problem of illegal immigration in Assam, and on August 15, 1985, the Assam Accord was signed by the governments at the center and state and AASU leaders. The accord, among other things, promised safeguards to protect and promote the cultural, social, linguistic identity of the Assamese people. Subsequently, disaffected Bodo tribal people (in Assam and Meghalaya), feeling overshadowed by the Assam Movement and its focus on the Assamese identity, agitated for an autonomous state. They were joined by the militant United Liberation Front of Assam (ULFA), which waged a vigorous guerrilla campaign for the outright secession of Assam from India.

In 1985 Mahanta helped form a new political party, the Assam People’s Council (Asom Gana Parishad; AGP), which won legislative elections in the state that year and formed a government with Mahanta as chief minister (head of government). There followed a period of greatly increased violence, which was attributed to the ULFA.

After 1990: Insurgency and the peace process

When it was revealed that AGP members had forged direct links with the ULFA, the national government in 1990 dismissed Mahanta’s government. The Indian army subsequently undertook a series of military campaigns against the separatists (1990–91), and membership in the ULFA was made a criminal offense. In 1992 a group of ULFA militants, who later came to be known as SULFAs (surrendered ULFA), entered negotiations with the government and surrendered. After a few years of the Indian National Congress being in power, the AGP, which had struggled with internal dissension after being ousted from power in 1990, again took control of the state government in 1996. The party had campaigned on a platform calling for greater autonomy and self-determination in Assam, but it came to oppose the ULFA. However, after it was learned that the AGP government had recruited former ULFA members to kill family members of ULFA leaders, the AGP was voted out of office in the 2001 legislative elections; the Indian National Congress party came to power for the next 3 terms (more than 15 years), with Tarun Gogoi as chief minister. The ULFA and other separatist groups continued guerrilla and terrorist activities into the 21st century, and the government stepped up counterinsurgency operations. The group, however, also engaged in discussions with government officials, which resulted in the signing of a preliminary peace agreement in 2011. Attacks continued throughout the following decade, especially from an increasingly independent faction within the ULFA, named ULFA (Independent), that opposed the peace negotiations.

In January 2020, central and state government officials signed an agreement with Bodo militants that awarded amnesty, recognized an autonomous Bodoland Territorial Region (BTR) within Assam, and offered significant funding for its development. Twelve years after signing the preliminary peace agreement, the pro-talks ULFA faction signed a tripartite peace accord with the state and central governments in December 2023. It was hoped that such a favorable agreement would also incentivize the “anti-talk” ULFA faction to join ongoing negotiations for a permanent agreement.

In 2016 the Bharatiya Janata Party (BJP) won the state elections for the first time, having made significant gains in the state in the 2014 Lok Sabha elections and performing well in municipal elections. The decline of the AGP, a new alliance with the Bodoland People’s Front (BPF), and in-fighting within the Congress, especially between Chief Minister Tarun Gogoi and senior Congress leader Himanta Biswa Sarma, who subsequently joined the BJP, also helped the BJP gain strength. The party went on to win two more consecutive assembly elections (2021 and 2026) in the state.

The table provides a list of all chief ministers of Assam.