Karachi is Pakistan's largest city and is the capital of Sindh; it lies on Pakistan's southern cost, on the Arabian Sea just northwest of the Indus River Delta . Originally a tiny fishing village, Karachi became a trading center in the 1700s. The British, after gaining control of the region in the 19th century, developed the city into an important port. Rapid growth came after Pakistan became independent in 1947, largely, because of the city having been historically the largest urban centre during British rule in regions forming modern Pakistan. Karachi was the national capital from 1947 until 1959. Over the next several decades it became one of the fastest growing cities in the world, doubling its population from 1981 to 1999.