The spread of Greek culture throughout most of the ancient world
Although Alexander the Great's kingdom did not last for long, his influence did. This is because the Greek were able to spread their culture throughout Europe and Asia. The Greek culture mixed with other civilization to for the Hellenistic culture that spread around Europe
Rome, Metropolitan City of Rome, Italy
Industrialization and/or Urbanization. We now have technology fields, and higher paying job fields, that seem more interesting or grabs the younger generations attention.
Naturalized citizens are mostly more politically involved and tend to participate in things like voting more. Naturalization has a positive effect on voter turnout. Naturalized citizens are often immigrants from areas where their rights are not respected so they move to other places where they are willing to participate in public affairs because the system suits them better.