A. Both, the Roman and the Aztec Empire were agrarian empires that exercised economic, political, and territorial control over a vast region and different cultures. The first great difference is the size, while the Roman Empire conquered all the land around the Mediterranean, including almost the entire Europe, North Africa, and the Middle East, the Aztec Empire was confined to a smaller region in Mesoamerica, in the center of what today is Mexico. Their political organizations were similar, a hierarchical pyramid with the emperor at the top and the slaves at the bottom. The Aztecs achieved a great knowledge in astronomy and built monumental constructions, but unlike the Romans, they did not develop written language, the wheel, nor iron. Another common element was that the arrival of Christianity meant the end of both empires.
B. Like Mesoamerican civilizations, Subsaharan cultures also built large empires, like the Great Kingdom of Zimbabwe and the Kingdom of Mutapa. These Mesoamerican and Subsaharan civilizations presented common elements, like the fact that they built agrarian empires centralized in the figure of a monarch with religious attributes. All these empires were based upon polytheistic religions, and none of them developed a system of written language nor wheel. A great difference was that Mesoamerican civilizations achieved great developments in astronomy, mathematics, and architecture, achievements that, in general, were more restricted in Subsaharan Africa. Mesoamerican and Subsaharan civilizations came to an end with the arrival of Europeans.