One can do a pretty decent job of explaining the larger course of history with an economically deterministic model (which in turn, although not necessarily in the case of the paper below, has a strong climate driven component).
We propose and test empirically a theory describing the endogenous formation and persistence of mega-states, using China as an example. We suggest that the relative timing of the emergence of agricultural societies, and their distance from each other, set off a race between their autochthonous state-building projects, which determines their extent and persistence.
Using a novel dataset describing the historical presence of Chinese states, prehistoric development, the diffusion of agriculture, and migratory distance across 1° × 1° grid cells in eastern Asia, we find that cells that adopted agriculture earlier and were close to Erlitou the earliest political center in eastern Asia remained under Chinese control for longer and continue to be a part of China today. By contrast, cells that adopted agriculture early and were located further from Erlitou developed into independent states, as agriculture provided the fertile ground for state-formation, while isolation provided time for them to develop and confront the expanding Chinese empire.
Our study sheds important light on why eastern Asia kept reproducing a mega-state in the area that became China and on the determinants of its borders with other states.
James Kai-sing Kung, et al., "Millet, Rice, and Isolation: Origins and Persistence of the World's Most Enduring Mega-State", SSRN IZA Institute of Labor Economics Discussion Paper Series IZA Discussion Paper No. 15348 (June 11, 2022).