The Sri Lankan Civil War occurred between 1983 and 2009, and started with an intermittent insurgency beginning in 1983 by the Tamil Tigers; the Tamil Tigers fought for an independent Tamil state due to continous discrimination and violent persecution of Sri Lankan Tamils by the Sinhalese dominated Sri Lankan Government.
The Indian government intervened in 1987 providing aid to the Tamil rebels and signing an agreement with the Sri Lankan government that providing concessions to the Tamil population in return for disarming. However, while many groups were willing to lay down arms, the Tamil Tigers were not and were involved in the assassination of Indian PM Rajiv Gandhi in 1991.
A peace process was initiated between 2002-2006 between the rebels and the government, that eventually broke down and led to a further period of conflict between 2006-2009.
Post the assassination of Rajiv Gandhi, the Indian state provided military and political support to the Sinhalese government. Furthermore, they undermined Tamil Tiger leadership by supporting alternative leaders.