One of the most important was climate changes. As climate changed, nomads had to find new places to migrate to which led to people going to areas that were uninhabited before. Another was the development of agriculture which more or less ended the nomadic way of life when people started settling.
In 98 BC Rome expelled all non-Roman citizens (except slaves). It was a time in Rome when the non-Romans were not allowed to stay in the city unless they were slaves. Rome was a place of religion and history no foreign outsiders were allowed.
Answer is bbhope this helps
