East Pakistan was a provincial state of Pakistan established in 14 August 1947. The provincial state existed until its declaration of independence

Bangladeshi Declaration of Independence

The independence of Bangladesh was declared by Sheikh Mujibur Rahman through a message on 26 March 1971 just before he was arrested at about 1:30 a.m....

 on 26 March 1971 as the independent nation of Bangladesh

Bangladesh

Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

. Pakistan recognized the new nation on 16 December 1971. East Pakistan was created from Bengal

Bengal

Bengal is a historical and geographical region in the northeast region of the Indian Subcontinent at the apex of the Bay of Bengal. Today, it is mainly divided between the sovereign land of People's Republic of Bangladesh and the Indian state of West Bengal, although some regions of the previous...

 Province based on the 'Mountbatten Plan' in what was then British India

British Raj

British Raj was the British rule in the Indian subcontinent between 1858 and 1947; The term can also refer to the period of dominion...

 in 1947. Eastern Bengal was given to the Dominion of Pakistan

Dominion of Pakistan

The Dominion of Pakistan was an independent federal Commonwealth realm in South Asia that was established in 1947 on the partition of British India into two sovereign dominions . The Dominion of Pakistan, which included modern-day Pakistan and Bangladesh, was intended to be a homeland for the...

 and became a province of Pakistan by the name East Bengal

East Bengal

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

.