After The Partition

Upon the Partition in 1947, India held the major ports and both sides of Pakistan had to develop a national port. Lahore was the largest city of the western half of Pakistan but Karachi was on the coast in a good location for the main port. The bulk of those relocated from India settled in Karachi and it became West Pakistan's largest city as it grew into the major port. In East Pakistan, now Bangladesh, it was Chittagram that became the major port. 

An important factor in the ports of India and Pakistan was the Suez Canal. This made ship travel and transport with the West much easier, which made the ports more important, and ships were more likely to come from the west, rather than the east. 

This made Karachi the ideal location for a port for Pakistan and Mumbai for India. We can see this in the population of the port cities. Kolkata (Calcutta) was long the most populous city of India but was eventually exceeded by Mumbai. Lahore was the largest city of Pakistan at Partition but was exceeded by Karachi. In Sri Lanka, Kandy was historically the most important city but was exceeded by Colombo, which was on the side of the island facing the Suez Canal. 

To understand the violence of the Partition we have to understand that the Second World War had just concluded and the barbarity of the outside world seeped into India. History tends to repeat itself and the Partition was repeated 24 years later in Pakistan, with the eastern half separating as Bangladesh. The Partition then repeated in Sri Lanka, with the Hindu Tamils of the north of the island seeking to separate from the Buddhist Sinhalese. Unlike the other two partitions this one was unsuccessful, with the civil war finally ending in 2009. Another repetition of the Partition is the separatist movement in the Pakistani province of Balochistan.