Tibet has always been the core issue in Sino-Indian relations. Even during the 1962 conflict, Chinese leaders, including Mao, acknowledged that the conflict was not about the boundary or territory but about Tibet. The revolt in Tibet leading to the flight of the Dalai Lama to India in 1959 came as a rude shock to the Indian leadership. After the 1962 conflict, the issue of Tibet went on the back burner. The revival of negotiations in 1981 brought the issue back into focus. The Chinese consistently tried to obtain reassurance from India that the Indian position on Tibet remained as before, and that India would not ‘meddle’ in Tibetan affairs and would control the activities of the Dalai Lama in India. Yet, boundary infringements by the Chinese continued. Sino-Indian border negotiations are stalemated and progress, if any, is at a snail’s pace. Thus, Tibet still remains the core issue.
https://www.idsa.in/system/files/jds_6_4_RSKalha.pdf