This research compares the peace processes in Manipur and Nagaland, two of the most violent states in the Indian Northeast. Nagaland has seen one of India's longest peace negotiations (starting with the Shillong Accord of 1975, ceasefires in 1997, and the Framework Agreement in 2015), while Manipur has witnessed fragmented non-state actors between Meitei, Naga and Kuki groups with little movement towards holistic peace. This paper examines why peace talks in Nagaland have been more successful and why ethnic violence and multiple peace talks continue in Manipur. Using comparative historical analysis, theories of conflict transformation and the state-society nexus, the paper examines the role of sovereignty (independence) claims, territorial, ethnic mobilisations, civil society activism and national government initiatives. The paper concludes that while Nagaland's peace process has evolved from a sovereignty claim into negotiated autonomy and shared sovereignty, Manipur's conflicts are fragmented because of competing claims around sovereignty, territorial integrity, ethnic homeland and lack of inter-ethnic trust. The paper argues that lasting peace in Northeast India needs multi-party negotiations, constitutional reform, mechanisms for inter-ethnic reconciliation and greater civil society involvement.