The Greater East Asia Co-Prosperity Sphere (大東亜共栄圏 Dai-tō-a Kyōeiken) was an imperial concept created and promulgated for occupied Asian populations during the first third of the Shōwa period by the government and military of the Empire of Japan. It promoted the cultural and economic unity of the East Asian race. It also declared the intention to create a self-sufficient "bloc of Asian nations led by the Japanese and free of Western powers". It was announced in a radio address entitled "The International Situation and Japan's Position" by Foreign Minister Hachirō Arita on June 29, 1940.

An Investigation of Global Policy with the Yamato Race as Nucleus — a secret document completed in 1943 for high-ranking government use — laid out the superior position of Japan in the Greater Asia Co-Prosperity Sphere, showing the subordination of other nations was not forced by the war but part of explicit policy. It explicitly states the superiority of the Japanese over other Asian races and provides evidence that the Sphere was inherently hierarchical, including Japan's true intention of domination over Asia.

At its largest extent, the Co-Prosperity Sphere covered most of East and Southeast Asia, including the Japanese Empire, Manchukuo, the State of China, the Kingdom of Thailand, French Indochina (Empire of Vietnam, Kingdom of Kampuchea, Kingdom of Laos), the Second Philippine Republic, large parts of the Dutch East Indies (State of Indonesia), British Hong Kong, Malaya and Burma (State of Burma), and parts of British India (Azad Hind) and the American Republics of Transpacifica and Alaska.

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