East Bengal was the name used during two periods in the 20th century for a territory that roughly included the modern state of Bangladesh. Both instances involved the violent partition of Bengal.

First Partition, 1905-1912

The first instance of the name was during the British rule of India. British governance of large swathes of Indian territory began with Robert Clive's victory over the nawab of Bengal, Siraj-ud-Daula, at the Battle of Plassey in 1757. The victory gave the British East India Company dominion over Bengal, which became the headquarters of British administration in the sub-continent. After the Indian rebellion of 1857 (known as the "Mutiny"), the British government took direct control away from the East India Co., and established its imperial capital at Calcutta, the city founded by the Company. By 1900, the British province of Bengal constituted a huge territory, stretching from the Burmese border to deep into the Ganges valley.

With the assumption of Lord Curzon to the office of Governor-General of India, British India was finally put under the charge of a man who considered himself an expert in Indian affairs. Curzon, seeing the logistical problems of adminstering such a large province, proposed to divide Bengal. Bengal, henceforth, would encompass Calcutta and the western territories, roughly comprising modern West Bengal, Bihar, and Orissa. East Bengal, the new province, would roughly encompass modern Bangladesh and the northeastern states of India (then all grouped under the heading of Assam).

While Curzon claimed the action was one merely founded upon administrative principles, the growing nationalist movement, which originated with the educated elite of Calcutta and the Bengali aristocracy, took the action as an attempt to cut off Bengal's Hindu intellectual leaders (based in Calcutta) from the majority Muslim agriculturalists of the east, dividing the nationalist movement along lines of class and religion. The partition of Bengal, effected in July 1905, sparked a firestorm in the nationalist movement. The partition was revoked in 1912, but it was accompanied by slicing off the non-Bengali portions of the province -- creating separate provinces for Assam and Bihar and Orissa -- and the shifting of the capital from Calcutta to Delhi.

Second Partition, 1947-present

In 1947, as part of the Partition of India, Bengal was divided into two states -- the majority-Hindu portion became the Indian state of West Bengal, and the majority-Muslim portion became the Pakistani province of East Bengal. In 1955, the government of Pakistan eliminated the provinces and changed the name of East Bengal to East Pakistan. The Liberation War of Bangladesh resulted in creation of the independent state of Bangladesh from the province of East Pakistan.