What are the reasons for the spread of slavery in Rome?

Slavery was the backbone of ancient Roman society. Slave labor produced most of the goods in the territory of the Roman state. A Roman citizen with fewer than three slaves was considered a poor man. Due to the fact that as the state developed, the Romans needed more and more slaves – they fought all new wars of conquest. The enslaved peoples had to work for generations for their masters. in the territory of the Roman Empire there were a great many slave markets where thousands of slaves from all over the world were bought and sold every day.