West Pakistan consisted of the western part of Pakistan from 1947 until 1971, when East Pakistan became Bangladesh and West Pakistan became the present-day Pakistan.

When the United Kingdom left India in 1947, Pakistan split from India to form a separate Muslim country. From 1947 through to 1971 the state consisted of two units: West Pakistan and East Pakistan, separated from one another by India. The capital Karachi was in the geographically larger though less populous West Pakistan.

General elections held in December 1970 polarized relations between the eastern and western sections of Pakistan. Though Muslim, the ethnic composition of the former East Pakistan differed from that of West Pakistan. The government of Pakistan before 1971 was dominated by West Pakistan, with the East Pakistanis considering themselves discriminated against in government. The Awami League, which advocated autonomy for the more populous East Pakistan, swept the East Pakistan seats to gain a majority in Pakistan as a whole. The Pakistan Peoples Party (PPP), founded and led by the former Foreign Minister, Zulfikar Ali Bhutto, won a majority of the seats in West Pakistan, but the country was completely split with neither major party having any support in the other area. Negotiations to form a coalition government broke down. Consequently, East Pakistan demanded independence, which led to civil war in 1971.

In that war, troops of West Pakistan, under Yahya Khan, killed an estimated 1.5 million people in an attempt to subdue the rebellion. India attacked East Pakistan and captured Dhaka in December 1971, when the eastern section declared itself the independent State of Bangladesh. Indian involvement in East Pakistan also led to fighting in West Pakistan and Kashmir, and this entire conflict was the third war between the two nations, the Indo-Pakistani War of 1971. Yahya Khan then resigned the presidency and handed over leadership of the western part of Pakistan to Bhutto, who became President and the first civilian Chief Martial Law Administrator.