This paper adopts a regional and geographical approach to show how the early spread of communism to mainland South-east Asia owes much to overseas Chinese and overland Vietnamese patterns of immigration. This wider approach seeks to get beyond the frontiers of nationalist histories and the formation of the 'modern' nation-state (whether colonial or national) in order to think in more material terms about how communism and not entirely unlike Catholicism or any other religion first entered mainland Southeast Asia on the ground, by which channels, by which groups of people and at which times. The idea is to begin mapping out the introduction and spread of communism in peninsular Southeast Asia in both time and space. This, in turn, provides us with a methodologically and historically sounder basis for thinking about the 'why' of this Sino-Vietnamese revolutionary graft and the failure of this brand of conmmunism to take hold in certain places and among certain peoples outside of China and Vietnam