The newly birthed Pakistan faced a number of immigration and naturalization difficulties due to the division of Punjab and Punjabi nation.
The Punjabi Hindus and Punjabi Sikhs were displaced from the western side of Punjab to the eastern side of Punjab and the Punjabi Muslims were displaced from the eastern side of Punjab to the western side of the Punjab.
In the riots which preceded the partition in the Punjab region, about 2 Million people were killed in the retributive genocide and 20 Million people were displaced.
The Time Magazine of September 1947 gave killing static around one million people. However, it was the largest genocide after the Second World War within a short span of time.
UNHCR estimates 14 million Muslim Punjabis, Hindu Punjabis, Sikh Punjabis were displaced during the partition; but, it was the largest mass migration in human history too.
In 1947, only the UP, CP politicians, bureaucracy and the establishment came in Karachi, the capital of Pakistan, to take the charge of Pakistan. In 1948, the students of Darul Uloom Nadwatul Ulama, Darul Uloom Deoband, and Barelvi institutions in Uttar Pradesh Province of India and the Students of Aligarh Muslim University with their families were brought into Pakistan through special trains by declaring them the Potential Immigrants from India. They were provided the services in teaching institutions and government departments of Pakistan. Students of Aligarh Muslim University were taken as the high-rank officers in the bureaucracy and the establishment of the government of Pakistan. In Karachi, the capital of Pakistan to settle them the first residential colony for them with the name of the PIB Colony was built by the Chief Minister of Sindh, Pir Illahi Bux (3 May 1948 to 4 February 1949).
After the death of Muhammad Ali Jinnah on 25 December 1948, the problem of religious minorities flared in Karachi and then in Uttar Pradesh Province of India, during 1949. The Liaquat Ali Khan took the advantage of the situation and started to create the atmosphere and circumstances to help the Urdu Speaking population of the Uttar Pradesh Province of India and to settle them in Pakistan.
Liaquat Ali Khan met the Indian Prime Minister Jawaharlal Nehru to sign the Liaquat-Nehru Pact on 8th April 1950 to protect the religious minorities on both sides of the border. But, in practical he started to patronize the infiltration of Urdu Speaking communities from the Uttar Pradesh Province of India to Pakistan on a mass scale.
After the Liaquat-Nehru Pact in 1950, the Urdu Speaking communities from the Uttar Pradesh Province of India started to infiltrate the Pakistan which polarized the West Pakistani population, especially in the cities of Karachi, Lahore, Rawalpindi, Multan, Hyderabad and other parts of the Punjab and Sindh Province.
In a matter of fact, the Liaquat-Nehru pact was for the settlement of dislocated Punjabis due to the division of Punjab and not for the people of other areas. Punjab was declared as an agreed area and other areas were declared as Non-Agreed areas for migration, but as a Prime Minister of Pakistan, Liaquat Ali Khan manipulated the agreement to settle the people of his native province in Lahore, Rawalpindi, Multan, Hyderabad and other parts of the Punjab and Sindh Province at large scale, especially in Karachi to control the capital and port city of Pakistan.
As the result of infiltration of Urdu-speaking communities from the Uttar Pradesh Province of India to Pakistan, in 1951, close to half of the population of the Lahore, Karachi, Rawalpindi, Multan, Hyderabad and other major cities of Pakistan were Urdu speaking infiltrators from India.
The independence of Pakistan in 1947 saw the settlement of Muslim Punjabis fleeing in western Punjab from the areas of eastern Punjab. The Urdu-speaking Muhajirs started to settle in Pakistan after Liaquat-Nehru Pact on 8th April 1950. They gave the northern Indian atmosphere to the city of Karachi. The Muslim Gujaratis, Konkani, Hyderabadis, Marathi, Rajasthani and Malayali Muslims, originally from Kerala in South India also fled India and settled in Karachi.
Even after the 1951 Census, many Muslim families from India continued migrating to Pakistan throughout the 1950s and even early 1960s. Research has found that there were three predominant stages of Muslim migration from India to West Pakistan.
The first stage lasted from August–November 1947. In this stage of migration, the Muslim immigrants originated from East Punjab, Delhi, the four adjacent districts of Uttar Pradesh and the princely states of Alwar and Bharatpur which are now part of the present state of Rajasthan. The violence affecting these areas during partition precipitated an exodus of Muslims from these areas to Pakistan.
The second stage (December 1947-December 1971) of the migration was from what are Uttar Pradesh, Delhi, Gujarat, Rajasthan, Maharashtra, Madhya Pradesh, Karnataka, Andhra Pradesh, Tamil Nadu and Kerala.
The third stage which lasted between 1973 and the 1990s was when migration levels of Indian Muslims to Pakistan were reduced to its lowest levels since 1947.
In 1959 the International Labour Organisation (ILO) published a report stating that between the periods of 1951-1956, a number of 650,000 Muslims from India relocated to West Pakistan.
The 1961 Census of Pakistan incorporates a statement suggesting that there had been a migration of 800,000 people from India to Pakistan throughout the previous decade.
Since 1950, after Liaquat-Nehru Pact has been a movement of Muslims from Uttar Pradesh India to Western Pakistan through the Jodhpur-Sindh via Khokhropar. Normally, traffic between India and West Pakistan was controlled by the permit system. But in huge quantity, these Muslims from Uttar Pradesh came without permits to West Pakistan via Khokhropar.
From January 1952 to the end of September, 53,209 Muslim emigrants came via Khokhropar. Most of these probably came from the Uttar Pradesh. In October 1952, up to the 14th, 6,808 came by this route. After that Pakistan became much stricter on allowing entry on the introduction of the passport system. From the 15th of October to the end of October, 1,247 came by this route. From the 1st November, 1,203 came via Khokhropar.
Indian Muslim migration to West Pakistan continued unabated despite the cessation of the permit system between the two countries and the introduction of the passport system between the two countries. A fair number of Muslims crossed into Pakistan from India, via Rajasthan and Sindh daily. Mostly they came from Uttar Pradesh and Rajasthan. It is evident that they came in for better chances of employment.
In 1952 the passport system was introduced for travel purposes between the two countries. The legal route was taken by unemployed but educated Indian Muslims seeking better fortunes in Pakistan, however poorer Muslims from India continued to come illegally via the Rajasthan-Sindh border until the 1965 India-Pakistan war when that route was shut.
After the conclusion of the 1965 war, most Muslims who wanted to come to Pakistan had to come via the India-East Pakistani border. Once reaching Dhaka, most made their way to the final destination-Karachi. However, not all managed to reach West Pakistan from East Pakistan.
The 1951 census in Pakistan recorded 671,000 refugees in East Pakistan, the majority of which came from West Bengal. The rest were from Bihar. By 1961 the numbers reached 850,000. In the aftermath of the riots in Ranchi and Jamshedpur, Biharis continued to migrate to East Pakistan well into the late sixties and added up to around a million. Crude estimates suggest that about 1.5 million Muslims migrated from West Bengal and Bihar to East Bengal in the two decades after partition.
Over on the India-West Pakistan border, in the aftermath of the Indo-Pakistani War of 1965, 3,500 Muslim families migrated from the Indian part of the Thar Desert to the Pakistani section of the Thar Desert. 400 families were settled in Nagar after the 1965 war and an additional 3000 settled in the Chachro taluka in Sindh province of West Pakistan. The government of Pakistan provided each family with 12 acres of land. According to government records, this land totaled 42,000 acres. According to a November 1995 statement of Riaz Khokhar, the Pakistani High Commissioner in New Delhi, the number of cross-border marriages was 40,000 a year in the 1950s and 1960s.