The Roman Empire was so successful and left behind so much evidence that it has become the foremost example of an ancient empire; in European tradition the embodiment of the ancient world that produced great human achievements that needed to be recovered. From the rise of the Republic to the fall of the Empire, Rome used military and political power to create one of the greatest milestones in the history of western Eurasia. Its size and power led to a diffusion of cultures throughout the region and allowed for the development and growth of Christianity, which outlived the empire that allowed it to flourish. As Rome became too large and started to split, Christianity continued on in both halves of the former empire, making it appear to be the only dominant force in the world. However, in the Counterpoint of this chapter, it becomes clear that through all the power and influence that Rome had, it was only part of a system of empires that stretched throughout Eurasia, and it had strong rivals in Iran, in the Parthian and Sasanid empires.