Karachi is ranked as a beta world city.[15][16] It was the capital of Pakistan until Islamabad was constructed as a capital to spread development evenly across the country and to prevent it from being concentrated in Karachi.[17] Karachi is the location of the Port of Karachi and Port Bin Qasim, two of the region's largest and busiest ports. After the independence of Pakistan, the city population increased dramatically when hundreds of thousands of Muslim Muhajirs from India and from other parts of South Asia came to settle in Karachi.[18]