Digest from Premier Chou En-lai (Zhou Enlai)'s Letter to Prime Minister Nehru (8, September, 1959)
"The so-called McMahon LIne was a product of the British policy of aggression against the Tibet region of China and has never been recognized by any Chinese Central Government and is therefore decidedly illegal. As the the Shimla Treaty, it was not formally signed by the representative of the then Chinese Central Government, and this is explicitly noted in the treaty. For quite a long time after the exchange of secret notes between Britain and the Tibet local authorities, Britain dared not make public the related documents, nor change the traditional way of drawing this section of the boundary on maps. This illegal line aroused the great indignation of the Chinese people. The Tibet local authorities themselves later also expressed their dissatisfaction with this line, and, following the independence of India in 1947, cabled Your Excellency asking India to return all the territory of the Tibet region of China south of this illegal line (the so-called McMahon Line). This piece of territory corresponds in size to Chekiang (Zhejiang)Province of China and is as big as 90,000 square kilometers. Mr. Prime Minister, how could China agree to accept under coercion such an illegal line which would have it relinquish its rights and disgrace itself by selling out its territory--and such a large peice of territory at that."
