As an academic field in its own right, the topic of border studies is experiencing a revival in university geography courses as well as in wider political commentary. Of course, something about the postmodernist sensibility readily embraces the ambiguity, impermanence, transience, and twilight nature of bordered spaces among the planet's 192 territorially defined states. But we have another motivation in assembling this book, one rooted in contemporary rivalries sited in one of the world's most open regions. Until recently, border studies in contemporary Southeast Asia ap--peared as an afterthought at best to the politics of interstate rivalry and national consolidation. The maps set out all agreed postcolonial lines. Meanwhile, the physical demarcation of these boundaries lagged. Large slices of territory, on land and at sea, eluded definition or delineation.