Sikkim became an Indian state in 1975, after a referendum which resulted in overwhelming support for the removal of monarchy and a full merger with India. The Indian annexation of Sikkim was not recognised by China during the time. In 2003, China indirectly recognised Sikkim as an Indian state, on agreement that India accept that the Tibet Autonomous Region as a part of China, though India had already done so back in 1953. This mutual agreement led to a thaw in Sino-Indian relations.