The division of Assam and creation of the predominantly tribal states of Mizoram, Meghalaya, Nagaland and Arunachal Pradesh left a residue of boundary problems, which continue to bedevil relations between the neighbours.
Each of Assam's border disputes has its own legacy of claims and counter-claims.
Meghalaya
The problem between Assam and Meghalaya started when the latter challenged the Assam Reorganisation Act of 1971, which gave Blocks I and II of the Mikir Hills or present-day Karbi Anglong district to Assam.
Meghalaya contends that both these blocks formed part of the erstwhile United Khasi and Jaintia Hills district when it was notified in 1835.
At present there are 12 points of dispute along the 733-km Assam-Meghalaya border.
Meghalaya bases its case on survey maps of 1872 and 1929 and certain notifications of 1878 and 1951 while Assam wants to go by the recommendations of the Churachand Committee which in turn has been rejected by Meghalaya.
Joint surveys of the disputed border segments have been undertaken in part and the chief ministers of both the states are scheduled to meet again on August 6 at Guwahati to discuss ways to resolve the dispute.
Arunachal Pradesh
Arunachal's grievance is that the re-organisation of North Eastern states, unilaterally transferred several forested tracts in the plains that had traditionally belonged to hill tribal chiefs and communities to Assam.
After Arunachal Pradesh achieved statehood in 1987, a tripartite committee was appointed which recommended that certain territories be transferred from Assam to Arunachal.
Assam contested this and the matter is before the Supreme Court.
Mizoram
Prior to 2020, though a border dispute existed, the situation along the Assam-Mizoram border had remained relatively calm, barring a few instances in 1994 and in 2007.
Following a border incident 2007, Mizoram declared that it does not accept the present boundary with Assam and that the inner line of the Inner Line Reserved Forest as described in the 1875 notification under the Bengal Eastern Frontier Regulation (BEFR) of 1873 should be the basis for delineating the border and not the 1933 district boundary demarcation which Assam wants to be enforced.
Following recent violence in which seven people, including six policemen, were killed, Assam government has said that it will file a suit in the Supreme Court
Nagaland
The longest-running border dispute in the North East is between Assam and Nagaland, which began soon after Nagaland became a state in 1963.
The Nagaland State Act of 1962 had defined the state's borders according to a 1925 notification when Naga Hills and Tuensang Area (NHTA) were integrated into a new administrative unit.
Nagaland, however, does not accept the boundary delineation and has demanded that the new state should also have all Naga-dominated area in North Cachar and Nagaon districts.
Since Nagaland did not accept its notified borders, tensions between Assam and Nagaland flared up soon after the latter was formed, resulting in the first border clashes in 1965.
This was followed by major clashes between the two states along the border in 1968, 1979, 1985, 2007 and 2014.
The Assam government had filed a case in the Supreme to resolve the border dispute and for a permanent injunction restraining Nagaland from encroaching areas within the constitutional boundary of Assam.
In 2005, the Supreme Court instructed the Central government to constitute a boundary commission to settle various inter-state boundary problems in the North East.
The Centre had earlier constituted two commissions, the Sundaram Commission (1971) and the Shastri Commission (1985), to settle the Assam-Nagaland border dispute. These commissions, however, failed to resolve the matter as the concerned states did not accept their recommendations.
Inter-state borders
- Assam-Arunachal Pradesh: 804.1 km bordering eight districts of Udalguri, Sonitpur, Biswanath, Lakhimpur, Dhemaji, Charaideo, Tinsukia and Dibrugarh.
- Assam-Mizoram: The two states share a 164.6-km border between the Assam's districts of Cachar, Hailakandi and Karimganj, and Mizoram's Kolasib, Mamit and Aizawl districts
- Assam-Nagaland: The two states share 512.1 km bordering four districts of Sivasagar, Charaideo, Jorhat and Golaghat.
- Assam-Meghalaya: The two states share 884.9 km bordering West Karbi Anglong, Dima Hasao, Morigaon, Kamrup Metro, Kamrup Rural, Goalpara, Dhubri and South Salmara.
