Mao Zedong first talked about his idea of the “three-part world” in his meeting with Kenneth Kaunda, President of Zambia, on 22 February 1974. He said that there were “three worlds.” The United States and the Soviet Union belonged to the first world. Japan, Europe, Canada, and Australia made up the second world. Asia (minus Japan), Africa, and Latin America belonged to the third world. China was a part of the third world, because politically and economically it was behind the rich nations. There it could only stay with the poorer ones. (40 Years of Chinese Communist Party Rule, p. 375)
In March 1974, when the Political Bureau convened to choose who should lead the delegation to the United Nations, Jiang Qing disagreed with the decision to choose Deng Xiaoping. On 27 March Mao Zedong wrote to Jiang Qing: “Choosing Deng Xiaoping is my idea; it is best that you do not object.” Deng Xiaoping’s speech to the special U.N. session was approved by the Political Bureau and reviewed by Mao Zedong. On 4 April Mao Zedong commented on the speech, “Good. I endorse it.”
Source: A Glossary of Political Terms of the People’s Republic of China, by Kwok-sing Li (Author), Mary Lok (Translator), published by the Chinese University Press (December 30, 1994).
Page 363, “Entry: The Theory of the Three-Part World”