This chapter focuses on the recent shift in historical perspectives concerning the mid-first millennium exchanges between the South China Sea and the Bay of Bengal and the subsequent new perspectives on the cultural evolution of this broad region. In particular, it reviews the results of recent research conducted on what appeared as the earliest complex trading-polities that developed in the Kra Isthmus from the late 5th-early 4th c BC. The discovery of their cosmopolitan and early urban nature, pushed back in time developments traditionally attributed to the early historical period. These trading polities produced or concentrated many of the shared cultural items distributed over a wide region. Their technological analysis demonstrated that most of these items were culturally hybrid, combining technologies and styles from various Asian horizons thus allowing to discuss further the concept of a pan-regional culture and cultural transfers. These research suggest that instead of envisioning cultural exchanges in terms of internal or external “influences”, those might be better understood as the product of joint-productions co-elaborated in a wider regionally connected area that constituted the Bay of Bengal and South China Sea interaction spheres.