Pakistan is a very diverse society with various ethnic and religious minorities.
At the time of Partition of British India in 1947, extensive reports of ill-treatment of Mohajirs including murder, rape, torture, land confiscation by Hindus as well as by Sikhs on their way from India to Pakistan galvanized the many ethnic groups of Pakistan to open their hearts and houses to accommodate the estimated 6-7 million refugees who streamed in. (Mohajirs: Muslims who migrated to Pakistan from various parts of India during the Partition of 1947).
Initially they suffered due to economic hindrances and obstacles having had to start from scratch in a new country but the government and people of Pakistan took many measures to offer them disproportionately key positions in the new country. Much land was allocated by the Government of Pakistan to facilitate the settling of the new refugees. Furthermore, several policies were enacted to further encourage the educated migrants to fill in vacancies within the country, a policy which remained in effect for quite some time allowing them to exert considerable influence as they came to hold most positions of power in the civil bureaucracy.
Furthermore, the national language of the new country was made Urdu, the mother tongue of the Mohajir community while the indigenous language(s) of Pakistan where often suppressed, many still don't have official recognition to this day. This led to further antagonism. This began to cause friction within Pakistan's multi-ethnic society which saw the unfair bias towards Mohajir's as suppression of their rights and privileges in their own country. A feeling of antagonism developed against the Mohajir population against whom many accusations where leveled. In the 1960s with the coming of General Ayub Khan and the official shifting of the capital of Pakistan from Karachi to Islamabad, Mohajirs sensed a conspiracy to deprive them of their rights and began to feel that their years of privilege were coming to an end.
Meanwhile, other communities already had a lingering sense of Mohajirs having far more prominence and power than their numbers deserved. Pakistan's indigenous communities including the Punjabi, Pashtun and Sindhi's who's literacy rates began rising, naturally represented more than 80% of the countries population but until the late 1960s, almost three quarters of the bureaucracy were still being held by the former refugees. Mohajir's also unfairly favoured hiring of people from within their own community over people's indigenous to Pakistan and often invited distant relatives from India to fill these spots over hiring of local peoples, this policy further increased resentment against these formerly welcomed refugees.
This sense of deprivation and anger increased with time that climaxed during the 1980s when ethnic tension and violence erupted pitting Pakistan indigenous ethnic groups against the Mohajir community. It reached its peak with the establishment of several parties representing and fighting for the rights Mohajirs, perhaps the most prominent and notorious being the violence prone MQM, a party accused by the US State Department of torturing, killing, extortion and of having links to terrorist groups. The group is known to receive considerable financial support from India's RAW intelligence agency and has carried out many subversive attacks against the state. As of July 2007, this party is one of the only groups to have openly supported and worked with the military dictatorship of President Pervez Musharaf, incidentally, a Mohajir himself born in India. Its current leader, Altaf Hussain is in hiding in England where he conducts the affair of the party from his London based office.
Recently, several Prominent Pakistani politicians travelled to England to press the British government to arrest and charge the leader of this party and expressed confusion as to why England was allowing a known terrorist to live in their country. The mohajir community is a diverse group consisting of many ethnic groups tied together by a common language of Urdu. It should be noted that many have successfully integrated into Pakistani society and publicly oppose the views and tactics of their co-linguists who they see as having been exploited by the criminal underworld and India's intelligence agencies. The Mohajirs overall, still have considerably rights in the country of Pakistan especially when compared to other refugee population such as the that of the Afghans, Iranians and Kashmiri's. They still enjoy considerable influence particularly vis-a-vis the media and print, and also in business and trade. The current president of Pakistan General Parvez Musharaf happens to be a mohajir as well as Prime Minister & Governor of Sindh.