Sui Dynasty

The Sui reunified China after nearly three centuries of division and then destroyed itself in a single generation — the same shape as the Qin eight hundred years earlier, and with the same result: a short brutal dynasty that built the infrastructure a long one would inherit. The Grand Canal is Sui. So is the rebuilt Great Wall, and the examination system in its first form.

It had two emperors who mattered and two empresses, and the two women could not have been less alike. One ran the state alongside her husband and made him swear he would father no child by another woman. The other watched her husband lose an empire and then survived him by thirty years, passed between five successive courts as a trophy.