This article challenges conventional notions of geography in Vietnamese historiography that overlook the role of the sea as an integrative social space capable of uniting ostensibly segregated regions economically, socially and politically. Viewing history from the seashore instead of the rice field, it highlights the littoral inhabitants who connected interior agricultural and forest foragers to coasting and ocean carrier trade, and underscores the importance of the littoral as the ‘great river’ that encouraged Vietnamese political expansion and state formation along a southern trajectory.