A series of letters between India’s then-Prime Minister Jawarhalal Nehru and Chinese Premier Chou En-lai (Zhou Enlai) on the disputed border regions along the Himalayas. The letters date between September 8 1959 and February 5 1960, two years before the Sino-Indian War broke out along the same boundaries being discussed here. The dispute has not since been resolved, with the latest skirmishes having broken out last year. The letters published here, by the Foreign Languages Press of Peking, are not the same as a separate Report of the Officials on the Boundary Questions, the latter covering a series of meetings between Indian and Chinese officials that took place earlier in 1959.
About the Sino-Indian border dispute (from Wikipedia):
The Sino-Indian border dispute is an ongoing territorial dispute over the sovereignty of two relatively large, and several smaller, separated pieces of territory between China and India. The first of which, Aksai Chin, is administered by China as part of the Xinjiang Uygur Autonomous Region and Tibet Autonomous Region and claimed by India as part of the union territory of Ladakh; it is a virtually uninhabited high-altitude wasteland in the larger regions of Kashmir and Tibet and is crossed by the Xinjiang-Tibet Highway. The other disputed territory is south of the McMahon Line, formerly known as the North East Frontier Agency and now called Arunachal Pradesh. The McMahon Line was part of the 1914 Simla Convention signed between British India and Tibet, without China’s agreement. As of 2020, India continues to maintain that the McMahon Line is the legal border in the east. China has never accepted that border, stating that Tibet was never independent when it signed the Simla Convention.
The 1962 Sino-Indian War was fought in both disputed areas. Chinese troops attacked Indian border posts in Ladakh in the west and crossed the McMahon line in the east. There was a brief border clash in 1967 in the region of Sikkim. In 1987 and in 2013, potential conflicts over the two differing Lines of Actual Control were successfully de-escalated. A conflict involving a Bhutanese-controlled area on the border between Bhutan and China was successfully de-escalated in 2017 following injuries to both Indian and Chinese troops. Multiple brawls broke out in 2020, escalating to dozens of deaths in June 2020.