The Greater East Asian Co-Prosperity Sphere is a international military and economic alliance, headed by Japan.
During the buildup to the Greater East Asian War and during its course, Imperial Japan set up numerous puppet states throughout Asia, manipulating local populations and economies for the benefit of Imperial Japan and backing the conception of a united Asia in the absence of (or opposed to) European influence. The term Greater East Asia had long been used in Japan to refer to all of East Asia. The original concept for the Sphere originated with General Hachiro Arita, a member of the Imperial Japanese Army and at the time Foreign Minister. His successor as foreign minister, Matsuoka Yosuke, formally announced the idea on August 1st, 1940, in a press interview, although in reality it had already existed in numerous forms. Leaders in Japan had long had an interest in the idea, in reality to extend Japanese influence and acquire a empire based on European models, ostensibly to free Asia from Imperialism.
As part of its war drive, Japanese propaganda contained phrases such as "Asia for the Asians!" and often reference the Sphere and the need to drive out European Imperialists. In some cases, Japanese troops where welcomed by locals, although in reality the brutal and racist Japanese soldiers where equal to or worse then the British and French they drove out. Japan built the sphere out of its vassals, intending to give themselves an economic and military advantage of the locals (one of the purported reasons for Japan's Invasion of China had been to gain an advantage over the Americans in the Chinese markets) without openly exposing their imperialist ambitions. By 1943, the Sphere included Manchukuo, Korea, Mengjiang and numerous territories originally held by France, Britain, Germany and China. In this period, it held an alliance with the Axis Powers. However, once the Greater East Asian War started, the Axis refused to intervene, causing relations to sour.
After the Greater East Asian War, the Sphere lost much former French Indochina back to France, who was later forced to return it to Thailand. Other loses include Japanese-occupied China (under the puppet state of Wang Jingwei regime). However the state of Mongolia entered the Sphere in 1951 of its own free will. This marked the start of the long process of changing the Sphere from a group of puppet states to a legitimate alliance.