During and after the independence period, Urdu speaking Muslims from India migrated in large numbers to Pakistan, especially to the port city of Karachi, which is today the largest metropolis in Pakistan. Migration from other countries, mainly from those nearby, has further accelerated the process of urbanisation in Pakistani cities. Inevitably, the rapid urbanisation caused by these large population movements has also created new political and socio-economic challenges. In addition to immigration, economic trends such as the green revolution and political developments, among a host of other factors, are also important causes of urbanisation. 