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Climate is definitely one. The weather has always influenced people to move, depending on what kind obstacles various weather conditions present for them. Job and career opportunities is another. People have migrated to find work for a number to years, though the idea of "work" has changed drastically since the 19th century and before. I can't think of any more right now, but if I do, I'll let you know!
Weather, jobs, food, and warfare/political climate. Are what I would consider four that are the same as what we do now.