The Roman empire was in many respects a cartel. In the Early imperial Period there was barely any regular bureaucracy, and the role of the governor was essentially to command the army, ensure taxation and act as a sort of upper circuit court. Power was maintained not through extensive political control but because the Roman army was extremely formidable and because, all in all, being part of the empire was convenient. Those who had the sort of political power to oppose Roman control tended to be the ones who benefited from it--after the conquest weeded out those for whom this was not the case, of course. The exceptions, such as Tacfarinas and Julius Civilis, were few, far between, and heavily concentrated in the uncertain frontier region.

Han China, on the other hand, while it did not have the sort of system that later developed in the Song, was still highly centralized and had an extensive bureaucracy. Even at the top of the pyramid there was a real distinction between private and public, which is not the case of the Roman elite. In many respects Han China was actually much more like a modern state than Rome was.

This is an increasingly large area of study, and Rome and China (ed Scheidel) is a major work in it.