Within four states of continental Southeast Asia and of the Theravada buddhist cultural area, Burma, Thailand, Laos, Cambodia, we observe the persistency of a concentric circle spatial model of uneven development and decreasing control of the central power. This model originates from the muang or principality of the precolonial period whose autonomy was challenged only by the rise of strong kingdoms (Burma, Siam). The colonization and the penetration of the capitalist economy did not succeed in truly integrating the national space in spite of the development of communication networks and of the rationalization of territorial administration. Thailand, not directly colonized, has gone the farthest in the way of a unified national territory because of the continuity of its monarchy and the integration of her Chinese bourgeoisie. The two buffer-states of Laos and Cambodia, and Burma are still economically underdeveloped and have a very loosely integrated external ring. The present trend for them is to become peripheries to Thailand and especially its center Bangkok where population, activity and capital accumulate.