This is False
Pre-Industrial Societies were not socially diverse due to poor transport and communication infrastructure.
E.g. it was not very often that would find Chinese Immigrants living in Europe and vice versa.
Trade did happen and there are instances of Arab trading communities living in China as far back as the 9th century. However, it was nothing like what we have today.
In large Empire such as Roman, Ottoman and Mughal Empires, we saw huge diversity of people who were part of the Empire but apart from that nothing comes close to the mass immigration we see today.
In Muslim Spain, students from all over Europe came to study in the universities and colleges, but there number was no where near what we see today.
The world really has opened up right now. The places that took weeks and months to travel, now takes only a couple of hours.