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Your challenge is for a scenario where an empire which controls the core areas of China (here is what the approximate extent of said empire would be like) which is majority Miao culturally and ethnically (at least among the ruling classes, so a Miao aristocracy ruling over a Han peasantry would be acceptable) with a POD after the rise of the Zhou Dynasty (so the POD would be later than 1050 BC). Bonus points if you manage it without any plagues or nomadic invasions which decimate the Han Chinese.