The essay addresses the international relations of the Southeast Asian región, with the purpose of identifying the main characteristics of its interaction with East Asia and the regional powers. The first part explores the origins of the term «Southeast Asia» and the regional order pre- World War II. The second and third sections focus on Cold War and post-Cold War developments, stressing the role of the Association of Southeast Asian Nations (ASEAN) as a vehicle for Southeast Asian relations with the Asia Pacific región. The fourth section examines Southeast Asian relations with the main powers: United States, China and Japan.