The study of South Asian and South Indian early historical exchanges has long been focused on connections with the West. Whilst exchanges with Southeast Asia have not been neglected, their study largely relied on the analysis of artistic influences and inscriptions of royal or mercantile nature. Most evidence suggests that close connections between Tamil Nadu and Southeast Asia began by the late 4th century AD. Excavations in Southeast Asia of first millennium BC and early centuries AD ports and hinterland sites, as well as the technological reconstruction of their craft systems, revealed that societies there experienced major evolutions paralleling those taking place in South Asia. Those include an early form of urbanization with water management and defensive systems, elaborate political organization, some being qualified as early States or city-States, complex economic bases with far-reaching networks. The parallelism of societal developments with obvious transmissions of concepts to Southeast Asia, as well as the knowledge of skilled Indian industries demonstrated by some Southeast Asian groups, shows that the links were already well established by the 4th century BCE, and thus began earlier. In this preliminary study, I will elaborate on different categories of evidence and make tentative interpretations on what are the economic and cultural implications.