What most of the people in East and West Pakistan had in common when they broke from India was that they were from Islamic religion.
The partition of India is the name by which we know a historical event that took place 70 years ago, on August 14, 1947, and that gave rise to the states of India and Pakistan.
This division was part of the end of British rule in the Indian subcontinent, known as the British Raj.
At the end of 1946, a year after the end of World War II and after almost a century of independence movements, Great Britain decided to end its political and military domination in British India. In June 1947, nationalist leaders Jawaharlal Nehru and Abul Kalam Azad, representing the Indian Congress, Mohammed Ali Jinnah on behalf of the Muslim League, BR Ambedkar as representative of the "untouchable" community and Tara Singh, representing the Sikhs , they agreed to divide the Indian subcontinent according to the predominant religions. This agreement was directly opposed to the ideas of Mohandas Gandhi, who dreamed of a united India. The predominantly Hindu and Sikh areas were assigned to the new state of India, while the predominantly Muslim areas formed the new nation of Pakistan. This division obeyed, in part, the Two Nations Theory, presented by Sir Syed Ahmed Khan in the 19th century and based on the religious division between Hindus and Muslims.
After the partition, Pakistan gained its independence on August 14, 1947, with Mohammed Ali Jinnah as its first Governor. The population of British India -390 million people- was divided: 330 million in India, 30 million in West Pakistan and another 30 in East Pakistan (today's Bangladesh). Once the borders were established, almost 15 million people crossed the borders into the territory with the corresponding religious majority: Hinduists to India and Muslims to Pakistan.