Rome’s conquering of the Greek city-states was a gradual process. See the timelines.
The Roman Empire itself began to decline starting around 200 CE.
The Fall of Rome didn’t happen in a day, it happened over a long period of time. There are a number of reasons why the empire began to fail. Here are some of the causes of the fall of the Roman Empire:
- The politicians and rulers of Rome became more and more corrupt
- Infighting and civil wars within the Empire
- Attacks from barbarian tribes outside of the empire
- The empire became so large it was difficult to govern
Rome Divides into Two
In 285 CE, Emperor Diocletian decided that the Roman Empire was too big to manage. He divided the Empire into two parts, the Eastern Roman Empire and the Western Roman Empire.
Over the next hundred years or so, Rome would be reunited, split into three parts, and split in two again. The culture that developed in the east is what we refer to as the Byzantine culture (330 CE – 1453 CE).
Finally, in 395 CE, the empire was split into two for good. The Western Empire was ruled by Rome, the Eastern Empire was ruled by Constantinople.
In 1453 CE the Ottoman empire overran Constantinople and the artists who had the ancient Greek and Roman traditions returned to Italy.
By 400 CE Rome was struggling under the weight of its giant empire. The city of Rome finally fell in 476 CE.
Map of Europe in the Early Middle Ages: Here.