The entire Sino-Indian border (including the western LAC, the small undisputed section in the centre, and the MacMahon Line in the east) is 4,056 km (2,520 mi) long and traverses one Indian union territory - Ladakh and four Indian states: Uttarakhand, Himachal Pradesh, Sikkim and Arunachal Pradesh.[4] On the Chinese side, the line traverses the Tibet Autonomous Region. The term was first used by Chinese Premier Zhou Enlai in a 1959 note to Indian Prime Minister Jawaharlal Nehru.[2] The demarcation existed as the informal cease-fire line between India and China after the 1962 war until 1993, when its existence was officially accepted as the 'Line of Actual Control' in a bilateral agreement.[5]