The ancient cultural threads that linked Thailand, Laos, Cambodia, and Myanmar—the so-called Indianized states in Southeast Asia—have long since frayed. Shifts beginning in the 1990s signaled yet another new regional order, which is still being formed. The end of the Cold War, the Cambodian peace agreement and the subsequent enlargement of ASEAN, the rise of China and India, a modest renewal of U.S. interest in Southeast Asia, and Myanmar’s reform process have forged new relations with old adversaries but also created new (or renewed) tensions. This chapter examines the transformation of the foreign relations of Thailand, Laos, Cambodia, and Myanmar in this new regional environment.