With the decision by Britain to withdraw from the Indian subcontinent, the Congress Party and Muslim League agreed in June 1947 to a partition of India along religious lines. Under the provisions of the Indian Independence Act, India and Pakistan were established as independent dominions with predominantly Hindu areas allocated to India and predominantly Muslim areas to Pakistan.
After India's independence on August 15, 1947, India received most of the subcontinent's 562 widely scattered polities, or princely states, as well as the majority of the British provinces, and parts of three of the remaining provinces. Muslim Pakistan received the remainder. Pakistan consisted of a western wing, with the approximate boundaries of modern Pakistan, and an eastern wing, with the boundaries of present-day Bangladesh.
The division of the subcontinent caused tremendous dislocation of populations; inter-communal violence cost more than 1,000,000 lives. Some 3.5 million Hindus and Sikhs moved from Pakistan into India, andabout 5 million Muslims migrated from India to Pakistan. In Punjab, where the Sikh community was cut in half, a period of terrible bloodshed followed. Overall, the demographic shift caused an initial bitterness between the two countries that was further intensified by each country's accession of a portion of the princely states.
Adding to the tensions, the issue of the polities Kashmir, Hyderabad, and the small and fragmented state of Junagadh (in present-day Gujarat), remained unsettled at independence. Later, the Muslim ruler of Hindu-majority Junagadh agreed to join to Pakistan, but a movement by his people, followed by Indian military action and a plebiscite (people's vote of self-determination), brought the state into India.
The nizam of Hyderabad, also a Muslim ruler of a Hindu-majority populace, tried to maneuver to gain independence for his very large and populous state, which was, however, surrounded by India.
After more than a year of fruitless negotiations, India sent its army in a police action in September 1948, and Hyderabad became part of India.
The Hindu ruler of Kashmir, whose subjects were 85 percent Muslim, decided to join India. Pakistan, however, questioned his right to do so, and a war broke out between India and Pakistan. A cease-fire was arranged in 1949, with the cease-fire line creating a de facto partition of the region.
The central and eastern areas of the state came under Indian administration as Jammu and Kashmir state, while the northwestern quarter came under Pakistani control as Azad Kashmir and the Northern Areas. Although a UN peacekeeping force was sent in to enforce the cease-fire, the dispute was not resolved.This deadlock has intensified suspicion and antagonism between the two countries.
In 1971, Pakistan was itself subdivided when its eastern section broke away and formed Bangladesh. Border disputes continue to embitter Pakistani-Indian relations, as Pakistan has produced a series of autocratic military rulers, while India maintained a parliamentary democracy.