The history of ancient Rome can be traced back to the 8th century BC to the 7th century BC. Before the 5th century BC, ancient Rome was in the primitive tribal stage. The period from 509 BC to the first 30 years was the Roman Republic, and the period from 27 BC to 476 AD was the Roman Empire. In the imperial era, ancient Rome became a great empire spanning Asia, Africa and Europe. Greece was also annexed by Rome in the 1 century, and Rome became the center of world culture.