This article looks at the music of a borderland region in Southeast Asia and how a particular drum accompaniment common to several local folk genres found there connects different social, linguistic, and/or religious communities. It focuses on the Andaman Coast of Malaysia and Thailand: a confluence of people and cultures in what was once a rural backwater prior to World War II but an area that has also long been exposed to contemporaneous cosmopolitan society from its neighbors in the region. These interrelationships produced a rich musical environment with a shared “Andaman” character, but as the twentieth century progressed and the region became divided along national lines, people and culture ceased to flow as they had previously. Legacies of a common Andaman Coast culture, however, remained extant despite being under-acknowledged. I explore those legacies through ethnographic and musical data from several cases that are united by a shared drumming practice. I refer to it as the changgong rhythm (borrowing the name of its best-known manifestation) and describe its archetypal features and appearances in four separate songs—including two mixed-sex social dances, a musical folk theater, and a ceremonial consecration, each of which holds an important position in the repertoires of its respective musical community. By using this musical phenomenon to bring attention to the common character and social networks of the Andaman Coast region (across borders, genres, and time), we can gain better understanding of some of the complex social dynamics that have shaped the region in recent decades, particularly in the transformations to the livelihoods, lifestyles, identities, and allegiances of its once-mobile populations.