Introduction

In the context of the end of the Cold War and the spread of globalism, sub-regions are attracting attention as new social units of international society never before observed. The starting point for our sub-region research was studies on the Pan-Japan Sea Region as a sub-region in Northeast Asia, which was advocated by the Association for the Japan Sea Rim Studies. Researchers in conventional border studies have been interested in the changes to national borders themselves and in the actors involved therein. In order to understand the functions of sub-regions that have not been institutionalized and the diverse aspects of sub-regions that differ according to region, it becomes essential to jettison Eurocentric teleological ideas. This chapter also presents overview key concepts of this book. The book deals with the relations between sovereign nations, sub-regions, and multilateralism. It examines the specific roles of civil society in the Mekong region, focusing on certain cases.