Following independence in 1948, G. G. Ponnambalam and the party he founded, the All Ceylon Tamil Congress (Tamil Congress), joined D. S. Senanayake's moderate, Western-oriented, United National Party Government. This Government pass the Ceylon Citizenship Act of 1948, which denied citizenship to Sri Lankans of Indian origin and resulted in Sri Lanka becoming a majoritanian state. Sri Lanka's government represented only the majority community, the Sinhalese community, and had marginalized the minorities, causing a "severe degree of alienation" among the minority communities.
When this Act was passed, the Tamil Congress was strongly criticized by the opposition Marxist groups and the newly formed Sri Lankan Tamil nationalist Federal Party (FP). S. J. V. Chelvanayakam, the leader of this new party, contested the citizenship act before the Supreme Court, and then in the Privy council in England, on grounds of discrimination towards minorities, but he did not prevail in overturning the act.
The FP took two seats in the 1952 election, against the Tamil Congress' four, but in the 1956 election it became the dominant party in the Tamil districts and remained so for two decades. The FP's came to be known for its uncompromising stand on Tamil rights. In response to the parliamentary act that made Sinhala the sole official language in 1956, Federal MPs staged a non violent sit in (satyagraha) protest, but it was broken up by a nationalist mob. The police and other state authorities present at the location failed to take action to stop the violence. The FP was cast as scapegoats and were briefly banned after the 1958 riots in which many were killed and thousands of Tamils forced to flee their homes.
Another point of conflict between the communities was state sponsored colonization schemes that had the effect of changing the demographic balance in the Eastern province in favor of majority Sinhalese that the Tamil nationalists considered to be their traditional homeland. It has been perhaps the most immediate cause of inter-communal violence.
In the 1970s importing Tamil language films, books, magazines, journals, etc. from the cultural hub of Tamil Nadu, India was banned. Sri Lanka also banned local groups affiliated with groups such as the Dravida Munnetra Kazhagham and the Tamil Youth League. Foreign exchange for the long established practice of Tamil students going to India for university education was stopped. Equally, examinations for external degrees from the University of London were abolished. This had the effect of culturally cutting off the links between Tamil Sri Lankan and Tamils from India. The then government insisted that these measures were part of a general program of economic self-sufficiency as part of its socialist agenda and not targeted against the Tamil minority.
In 1973 the policy of standardization was implemented by the Sri Lankan government to what they believed was to rectify disparities created in university enrollment in Sri Lanka under British colonial rule. It was in essence an affirmative action scheme to assist geographically disadvantaged students to gain tertiary education. The resultant benefits enjoyed by Sinhalese students also meant a significant fall in the number of Tamil students within the Sri Lankan university student populace.
In 1973, the Federal Party decide to demand for a separate state. To further their nationalistic cause they merged with the other Tamil political parties to become the Tamil United Liberation Front (TULF) in 1975. On 1976, after the first National convention of the Tamil United Liberation Front, the Ceylon Tamils moved towards a morphed nationalism which meant that they were now unwilling to live within a confined single island entity. Chelvanayakam and the Federal Party had always campaigned for a unitary country and thought that partitioning of the country would be “suicidal” up until 1973. However policies by the various governments that was considered to be discriminatory by Tamil leadership modified the stand to Tamil Nationalism.