The provinces had a special importance in the economy of Rome because the economy of Rome was based on agriculture and slaver.
Slavery in Rome was important for the economy and also for the social constitution of the society, it has served for the domination of Rome. Millions of slaves were transported to Rome in the Italian countryside and in the Latin colonies of all Europe. Slavery was widespread throughout the city, but mostly on farms and plantations where it had its greatest effect. The Romans used a limited form of rotation, and agricultural production was largely low-yielding and required a large number of slaves to function.
The economy of Rome was largely based on small-scale