The kind of arguments raging about migrants crossing the Channel to enter Britain illegally never raged in the Ancient Roman world. The reason is quite simple: borders, in as much as they existed, weren’t controlled. Romans did their best to negotiate entry and settlement for armed tribal groups, many of whom they welcomed into the army. Otherwise, individuals and families came and went as they liked. The point is that newcomers were essential — they kept numbers up (Rome required about 10,000 immigrants a year net, not including slaves) and were not a ‘drain on the economy’ because the welfare state did not exist. If they could not carve out a living for themselves, no one would do it for them.
In Rome itself, two professions were actively welcomed — doctors and teachers, the latter because the purpose of education was practical: to prepare the elite for success in law and politics by inculcating the art of persuasion. But Rome was always open to people with talent wherever they came from and whatever they did. As Seneca pointed out, it served some wishing to indulge their vices, others keen to display their virtues.
As the centre of empire, Rome was a magnet for ambitious politicians and administrators; as the largest single market, it attracted traders, craftsmen, builders and entertainers. The poet Martial wrote of the pulling power of its games, which drew in spectators from Bulgaria, Romania, Egypt, Britain, Arabia, Turkey, Ethiopia and Germany. Though the sheer number of slaves reduced opportunities at lower levels of employment, there was still a call for workers on building sites and quaysides, and for those with particular skills that served the elite — makers of luxury goods, sculptors and so on.