Back on initial topic:

It is known that Julius Caesar tried to stimulate the melting pot effect. He wanted his veterans to settle in foreign lands, to make sure that the local population got used and mixed up with the Romans. (That's why Caesar was ahead of his time: he thought in terms of Empire and provinces and not in terms of the city).

Secondly, Romans always let the conquered civilizations keep their gods, and add them to the Roman '' book of gods ''. This way, even religion mixed, which is again proof for the statement that Romans tried to mix up cultures as much as possible.