In answering this question, I would recommend that you consult your own textbook or class notes because there may be specific geographic and cultural advantages that you are supposed to know. Historians do not necessarily all agree about why Greece and Rome were able to become so successful. That said, I will discuss four factors that could be cited as reasons for these civilizations’ success. I will also discuss why it is hard to claim that each of these factors is important.
Textbooks commonly say that Greece succeeded because its geography forced it to become a maritime power. Greece’s terrain is very mountainous and it is only easy for people to live near the ocean. The mountains also make it very difficult to get from place to place in Greece by land. For these reasons, it was relatively easy for the Greeks to take to the sea. This allowed them to spread out and colonize areas around the Mediterranean.
Textbooks also say that Rome benefitted from its geography. They say that Italy’s location allowed Rome to spread to the east and west in the Mediterranean. Its location also allowed it to serve as a center of trade. They say that the shallow rivers of Central Italy and the mountains of the peninsula made it hard for anyone to invade and conquer Rome.
However, there are issues with taking these claims at face value. For example, both civilizations had the same location before and after they were strong. If geography helped them succeed, why did it only help them at very specific times? As another example, there were other civilizations, like the Etruscans, who lived in Italy. If Italy’s location was so great, why didn’t they create a major empire of their own? Clearly, geography cannot be the only answer to the question of these civilizations’ successes.
It is even harder to identify cultural factors that allowed Greece and Rome to succeed. We tend to look at culture in hindsight. We see a civilization that succeeded and we decide that its culture was somehow more suited to success than other cultures. In addition, it is not easy to know what Greek and Roman cultures were like in comparison to other cultures of their time.
One aspect of these cultures that could have helped them succeed was their willingness to give their people some degree of say in their government. The Athenian democracy and the Roman Republic did a good job of making sure that the people of those civilizations supported their government. They did not feel oppressed by their government and were (we can argue) more likely to work and fight hard for their country.
Another thing that allowed Rome to flourish was its ability to assimilate other cultures. In general, when Rome conquered other peoples, it did not keep them subjugated. Instead, it allowed them to become part of Rome, giving them a stake in Rome’s success. This made it less likely that the conquered people would rebel and destabilize the empire.
All of these are possible advantages that Rome and Greece had. However, it is probably a good idea for you to check your text and notes to see if your teacher expects you to give specific answers to this question.