Why was overseas trade important to the early southern Indian states?

Overseas trade was vital to the early southern Indian states because the region's geography and existing agricultural technology made the development of large, agrarian-based kingdoms—like those found in northern India—largely unfeasible.1

While the cultivation of rice provided a foundational base for economic change, it was insufficient to sustain the scale of statehood seen elsewhere. Consequently, trade played more than a marginal role in the economy, and overseas commerce became a major economic activity that provided considerable momentum for these states. This maritime focus allowed southern kingdoms to thrive by engaging with the Yavanas (Greeks and Romans) and, following the decline of Roman trade, shifting their maritime interests toward Southeast Asia.1