At its apex, the ancient Roman Empire included 50-60 million people - all under the absolute rule of the Emperor. They were all citizens of Rome, but they descended from a complex mix of sundry ancient tribes and nationalities: Gauls, Dacians, Armenians, Mesopotamians, Syrians, Africans, Egyptians, Britons, Spaniards, Germans, and so on. Roman citizens formed an immense and bewilderingly complex mosaic of languages, histories, creeds, and customs. Some willingly submitted to Roman authority, most were managed by the colonial firmness of the Roman state, and a few were continually at odds with the system that had conquered them. Which of the following best states the main idea of the passage?