I believe that it was the Pax Romana that allowed the Romans to combine into one unit. It allowed the Romans to have a break from all of their strife and struggle to focus on the values and structure of their society. The Pax Romana was a two hundred year period of time where there was relative peace. There was almost no war with outside invaders and this time of peace was important because it allowed them to make advancements because they weren't fighting the whole time. Though converging into a city-state created lots of spiritual and political repercussions, they recognized that as opposed to looking to be better than another place, they had to be a better self.
The character of Rome was originally formed through three centuries of constant warfare, and during this time they valued simplicity, seriousness and dignity. They also valued the worshipping of the gods, performing their duty to the state and to one’s family. This shows that the Romans could not survive through these tough times with constant warfare and were only able to get through it with their loyalty to their gods, state, and family. Simplifying more and more created more of a passion and stamina for the Romans. So when they were simply in one unit, it was easier for the Romans to stand strong and connected with the place that they lived.
