In comparative-historical analysis, countries are always different places before critical junctures set them on divergent pathways. By comparing the legacies of politicized ethnic diversity for the construction of state infrastructural power in Latin America and Southeast Asia, we elaborate the methodological and substantive importance of these "critical antecedents." The critical antecedent in each region was the inheritance at independence of a sharp indigenous cleavage. This indigenous inheritance shaped threat perceptions and state-society coalitions in both regions in similarly powerful path-dependent ways—yet in intriguingly divergent directions. A salient indigenous cleavage hindered but did not preclude state building in nineteenth-century Peru, while fostering but not predestining state building in post–World War II Malaysia. Divergent levels of postcolonial state infrastructural power thus exhibit deep if indirect foundations in the identity cleavages inherited from preindependence eras. This cross-region comparative exploration highlights the analytical leverage gained from systematically incorporating preexisting cross-case differences into critical juncture accounts.