Pan-Asian means having to do with all Asian peoples. Various ideologies promoting the unity of all Asian people are also referred to as Pan-Asianism. The prefix pan- by itself means relating to all of the people or places of a given group.
While Pan-Asian by itself just means the union of Asian peoples, Pan-Asianism as a philosophy is frequently used in the context of uniting against Europeans and the West. In 1924, famed Chinese nationalist Sun Yat-Sen called for "Greater Asianism" to resist European imperialism and win independence for Asian nations. Japan was also a vocal supporter of Pan-Asianism during the early 20th century, and during World War II, the nation referred to its conquests in Southeast Asia and the Pacific as the Greater East Asia Co-prosperity Sphere in an attempt to legitimize its invasions and promote the belief that it was looking out for other Asian peoples despite the atrocities Japan committed against them
Pan-Asianism continues to exist today. The Association of Southeast Asian Nations, ASEAN, was originally founded to stop the expansion of communism in the area, but today it serves to promote regional stability, economic prosperity and social progress, and it has even expanded to include socialist-communist states like Laos and Vietnam. Former Singaporean Prime Minister Lee Kuan Yew and other thinkers have also promoted Pan-Asian values in contrast to the belief systems of the West.