Migration is as old as humanity. Our first ancestors spread around the globe by slowly migrating. Migration continued to occur, often for very similar reasons compared to today. Fleeing from violence and invaders was oftentimes the reason (Germanic tribes fleeing from the Huns). Economic reasons had mostly to do with continued periods of drought, since pre-industrial economies were very similar. During the industrial revolution large parts of the rural population migrated into cities in a process called urbanization. This process can still be seen today