<p>The land of what is today Vietnam witnessed the emergence of three early kingdoms during the third century BCE, all decentralized tributary networks of distinct polities. After resisting the colonization of historical China throughout the first millennium, historical Vietnam started to build a unified nation in the Red River Delta following the Sinic model of political centralization and cultural standardization, while the other two kingdoms continued with their decentralized networks. From the eleventh to the eighteenth centuries, historical Vietnam gradually expanded its territory from the Red River Delta to the Mekong River Delta and imposed its model of political centralization and cultural standardization on this new land. Using nighttime light intensity as a proxy for economic prosperity, the present paper uncovers that areas that were governed longer by the centralized state of historical Vietnam were richer in the agricultural economy in the early 1990s, but poorer in the early 2010s after two decades of industrialization. A theoretical framework linking cultural assimilation to economic development can account for this reversal of fortune.</p>