Pre-19th Century :
The area which is now Bangladesh has a rich historical and cultural past, the product of the repeated influx of varied peoples, bringing with them the Dravidian, Indo-Aryan, Mongol-Mughul, Arab, Persian, Turkic, and European cultures. About 1200 A.D., Muslim invaders under Sufi influence, supplanted Hindu and Buddhist dynasties, and converted most of the population of the eastern areas of Bengal to Islam. Since then, Islam has played a crucial role in the region's history and politics. In the 16th century, Bengal was absorbed into the Mughul Empire.

Portuguese traders and missionaries reached Bengal in the latter part of the 15th century. They were followed by representatives of the Dutch, the French, and the British East India Companies. During the 18th and 19th centuries, especially after the defeat of the French in 1757, the British gradually extended their commercial contacts and administrative control beyond Calcutta into the remainder of Bengal and northwesterly up the Ganges River valley. In 1859, the British Crown replaced the East India Company, extending British dominion from Bengal in the east to the Indus River in the west.

19th Century
In the late 19th and early 20th centuries, Muslim and Hindu leaders began to press for a greater degree of independence. At the movement's forefront was the largely Hindu Indian National Congress. Growing concern about Hindu domination of the movement led Muslim leaders to form the All-India Muslim League in 1906. In 1913, the League formally adopted the same goal as the Indian National Congress: self-government for India within the British Empire. The Congress and the League were unable, however, to agree on a formula to ensure the protection of Muslim religious, economic, and political rights. Over the next 2 decades, mounting tension between Hindus and Muslims led to a series of bitter intercommunal conflicts.

20th Century
The idea of a separate Muslim state emerged in the 1930s. It gained popularity among Indian Muslims after 1936, when the Muslim League suffered a decisive electoral defeat in the first elections under the 1935 constitution. On March 23, 1940, Muhammad Ali Jinnah, leader of the Muslim League, publicly endorsed the "Pakistan Resolution" that called for the creation of an independent state in regions where Muslims were a majority.

At the end of World War II, the United Kingdom, under considerable international pressure to reduce the size of its overseas empire, moved with increasing urgency to grant India independence. The Congress Party and the Muslim League could not, however, agree on the terms for drafting a constitution or establishing an interim government.