A country of South Asia. Occupying land crisscrossed by ancient invasion paths, Pakistan was the home of the prehistoric Indus Valley civilization, which flourished until overrun by Aryans c. 1500 bc . After being conquered by numerous rulers and powers, it passed to the British as part of India and became a separate Muslim state in 1947. The country originally included the Bengalese territory of East Pakistan, which achieved its separate independence in 1971 as Bangladesh. Pakistan became a republic in 1956. Islamabad is the capital and Karachi the largest city.