In 1792 the French monarchy collapsed. Between 1799 and 1815, a new Parisian regime improved the efficiency and penetration of the central apparatus, while dramatically extending French military power. Short-lived though France's conquests were, her continental wars precipitated imitative reforms of administrative and military structures across Europe and a permanent reduction in the number of independent states.
Between 1752 and 1786 the Burmese, Siamese, and Vietnamese kingdoms all disintegrated. In each realm, a new, more dynamic leadership then succeeded in quelling the chaos, increasing the resources and local authority of the state, and enlarging its territorial writ. The ensuing wars between reinvigorated empires in the late 18th and early 19th centuries accelerated competitive reform while diminishing the number of independent polities across mainland Southeast Asia.
How shall we explain these parallels between Europe and Southeast Asia? Surely, one is tempted to say, no explanation is needed: the cultural contexts were so different, the interstate and domestic systems so unique, the trajectories so disparate as to render parallels ultimately meaningless. This is historical flotsam, curious but basically random coincidences, like similarities between Meso-American and Egyptian pyramids or between Jewish and Buddhist cosmogonic explanations for the origin of suffering.
But closer scrutiny suggests rather more was involved. In fact, in mainland Southeast Asia as well as in France, the late 18th and early 19th centuries ended the third and inaugurated the last of four roughly synchronized cycles of political consolidation that together spanned the better part of a millennium.