What are the conditions that immigrants are leaving in their home countries?

Conditions that immigrants are leaving in their home countries include: violence sparked by political or ethnic issues, political instability, absence of democracy, social instability, dependence on other countries, lack of access to basic resources such as food and/or water, lack of basic infrastructure, and economic instability.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place