either India or Pakistan. Cooch Behar district was merged in 1949 with India. The desire to "de-enclave" most of the enclaves was manifested in a 1958 agreement between Jawaharlal Nehru and Feroz Khan Noon, the respective Prime Ministers, for an exchange between India and Pakistan without considering loss or gain of territory. But the matter then worked into a Supreme Court case in India, and the Supreme Court ruled that a constitutional amendment was required to transfer the land, so the ninth amendment was introduced to facilitate the implementation of the agreement. The amendment could not be passed because of objections to the transfer of the southern Berubari enclave. Because of India's deteriorated relations with Pakistan, the issue remained unsolved. Negotiations restarted after East Pakistan became independent as Bangladesh in 1971 following the Bangladesh Liberation War. Agreement The Land Boundary Agreement was signed on 16 May 1974 between Indira Gandhi and Sheikh Mujibur Rahman which provided for the exchange of enclaves and the surrender of adverse possessions. Under the agreement, India retained the Berubari Union No. 12 enclave while Bangladesh retained the Dahagram — Angorpota exclaves with India providing access to it by giving a corridor, called the Tin Bigha Corridor. Bangladesh quickly ratified the agreement in 1974 but India failed to do so. The issue of the undemarcated land boundary of approximately in three sectors — Daikhata-56 in West Bengal, Muhuri River-Belonia in Tripura and Lathitila-Dumabari in Assam — also remained unsolved. The Tin Bigha Corridor was leased to Bangladesh in 1992 amid local opposition. The list of enclaves was prepared in 1997 by the two countries. Two Joint Boundary Working Groups were formed to work out the details of enclaves in 2001. A joint census was carried out in May 2007. In September 2011, India signed the Additional Protocol for the 1974 Land Boundary Agreement with Bangladesh. Both nations announced an intention to swap 162 enclaves, giving residents a choice of nationality. Under the agreement, India received 51 of the 71 Bangladeshi enclaves (from 51 to 54 of the 74 chhits) that were inside India proper (), while Bangladesh received 95 to 101 of the 103 Indian enclaves (111 out of 119 chhits) that were inside Bangladesh proper (). Bangladesh retained the of its Dahagram-Angarpota exclave. India acquired adverse possession areas and transferred adverse possession areas to Bangladesh. After the exchange of enclaves, India lost around 40 km2