The geographic factor was actually their location.
The industrial revolution indeed was a great factor in the growth of population in industrialized countries. The population in industrialized countries had a sudden rise or increase due to the bigger and greater opportunities provided by the country thus, alluring more people to migrate.
Muslims, Magyars, and Vikings all invaded and broke the empire
The draft. when you turn 18 as a male you have to register for the war. If there is a war or anything and they need people they will draft you to go.
