Status Updates From Historical Dynamics: Why St...

During the centralization ​phase, when the elite/general population ratio is favorable, the imperial core elites ​are likely to be open to the entry
of peripheral aspirants - highly ​conducive to strong pressures for assimilation. Decentral​ization phase, imperial elites close their ranks against newcomers, who then have no choice but to build alternative power net​works, and challenge the established order.

the theory of ​asabiya - the capacity of a group for collective action. the ​hypothesis that asabiya increases on metaethnic frontiers and declines in the core ​regions of large polities

Heightened sociopolitical instability depresses birth rates, resulting in a smaller cohort and, consequently, less competition among the next generation. The next ​generation, therefore, does well economically, has a lower mobilization potential, ​but also produces a large number of babies. Such a mechanism should lead to an ​alternation of small/docile versus
large/belligerent generations.