This chapter describes the circumstances that led to the multiple waves of humans out of Africa and spreading across the Earth. It explains how anatomically modern humans expanded their range from refuges in Africa into the Levant, spreading slowly east into central Asia and the far east, through to the Indonesian archipelago and into Australia. Another wave of modern humans also moved northwest into Europe. There, modern humans encountered descendants of previous migrations of hominis, likely Homo erectus. These were the Neanderthals, the Denisovans, and likely other archaic hominis. There is growing evidence that these early humans interbred with the hominis they encountered, forming incomplete hybrids that live on today. After this melding of humanity, the descendants moved on to colonize nearly every location on Earth, transitioning from hunter-gather communities to agricultural societies of increasing complexity.