Social, cultural and economic factors influence fertility, mortality and migration rates. Migration is affected by various factors like age, sex, marital status, education, occupation, employment etc. Age and sex are main demographic factors that affect the migration.
Ir is the third opinion, 100km area
It was caused by a mix of different scenarios. Rome was constantly attacked by Barbarian tribes; they were over-expanded, which made it really hard for them to keep their entire empire under control; they had a lot of economic problems and relied too much on slave labor; and they spent way too much money on their military, just to name a few factors.
