With an increasing regional integration and development, there are many competing ideas of, and proposals for, regional development in Asia. This article examines the historical evolution of the idea of regionalism, the meanings of Asian regionalisms, variations of Asian regionalisms and their impact on regional cooperation in East Asia. It discusses Mahathir's idea of neo-Asianism, Japanese new Asianism, Chinese ideas of regionalism, and variations of Korean ideas of regionalism. It also examines a normative basis of regionalism with special reference to the sovereignty question. The paper concludes that behind East Asian regionalism is nationalism which constitutes driving forces for regionalism; that two competing orders (Asia-Pacific regionalism versus pan-Asianism) create different expectations and visions of how East Asia region should evolve and they are in tensions and lead to different directions; and that East Asia lacks a convincing and acceptable normative framework.