The hills cover 5,200 square miles of inhospitable land bordering Burma and the northeastern Indian states of Tripura and Mizoram.
The chief minister of Tripura, S. R. Majumder, said the accord would bring peace and stability to the state, bordering Bangladesh. Authorities estimate nearly 600 died during the insurgency.
They walked four days to reach Takumbari, the largest of seven refugee camps in Tripura.
The problem started in 1951 with the steady influx of settlers from Bangladesh and other parts of India into Tripura.
It said seven deaths were reported from the northeastern state of Tripura, which borders Bangladesh, in fighting between members of the Congress Party and the Marxist Communist Party.
The surrender follows a negotiated settlement Aug. 12 by the Tripura state governement and the federal government with the insurgents.
Belonia Hills is the region in India's Tripura state that faces the Chittagong Hill Tracts.