Which city was the first capital of Pakistan? ?

After the separation, when Pakistan came into being, Karachi was considered as the capital of Pakistan but later on, it shifted to islamabad. The population of Karachi is about to 14.91 million. The area of Karachi is about to 3780 kilometer square. Karachi is very important for Pakistan, due to karachi port. Because many Pakistani do imports and exports through this port.