No region in Pakistan uses Urdu as its mother tongue, though it is spoken as the first language of Muslim migrants (known as Muhajirs) in Pakistan who left India after independence in 1947. Urdu was chosen as a symbol of unity for the new state of Pakistan in 1947, because it had already served as a "lingua franca" among Muslims in north and northwest British India. It is written, spoken and used in all provinces/territories of Pakistan, although the people from differing provinces may have different native languages.