TIN BIGHA CORRIDOR

According to the Indira Gandhi-Sheikh Mujibur Rahman treaty of 1974, india  and Bangladesh  were to hand over the sovereignty of the Tin Bigha Corridor (178 x 85 sq m) and South Berubari (7.39 km²) to each other, thereby allowing access to the Dahagram–Angarpota enclaves and the Indian enclaves adjacent to South Berubari. Bangladesh did hand over the sovereignty of the smaller South Berubari to India instantly in 1974. India, however, refused to transfer the Tin Bigha Corridor to Bangladesh.
After much Bangladesh  government protest, India, instead of handing over sovereignty in 2011, proposed to lease the Tin Bigha Corridor to Bangladesh  for a certain time. South Berubari, meanwhile, would remain in the possession of India.
The total area of South Berubari Union No. 12 is 22.58 km². of which 11.29 km. was to go to Bangladesh. The area of the four Cooch Behar enclaves which would also have to go to Bangladesh was 6.84 km². making the total area to be transferred 18.13 km². The population of the area including the four enclaves to be transferred, as per 1967 data, was 90% Hindu. The Bangladesh enclaves, Dahagram  Angorpota, were to be transferred to India. Their total area was 18.68 km². and as per 1967 data more than 80% of their population was Muslim. If this exchange had gone through, it would have meant a change of nationality for the population or migration of the population from Dahagram and Angorpota and South Berubari Union No. 12 and consequent serious rehabilitation problems. There were in any case major agitations by the people of Berubari protesting against the transfer.
After 1971, India proposed to Bangladesh that India may continue to retain the southern half of South Berubari Union No. 12 and the adjacent enclaves and, in exchange, Dahagram and Angorpota may be retained by Bangladesh. As part of the package a strip of land would be leased in perpetuity by India to Bangladesh, giving her access to Dahagram & Angorpota in order to enable her to exercise sovereignty on these two enclaves. This was accepted by Bangladesh as part of a carefully constructed Land Boundary Agreement signed by Prime Minister Indira Gandhi and Prime Minister Sheikh Mujibur Rahman in May 1974. The Berubari dispute was thus finally resolved by Article 1.14 of the Agreement which stated:
"India will retain the southern half of South Berubari Union No. 12 and the adjacent enclaves, measuring an area of 2.64 square miles approximately, and in exchange Bangladesh will retain th Dahagram and Angorpota enclaves. India will lease in perpetuity to Bangladesh an area of 178 metres x 85 metres near 'Tin Bigha' to connect Dahagram with Panbari Mouza (P.S. Patgram) of Bangladesh."