By about 9,000 to 7,000 years ago, agricultural techniques including farming and herding had spread from the places they had developed into surrounding regions. The best-studied of these spreads is from the fertile crescent into Europe (but we can assume expansion in other regions happened over similar time-scales and in similar ways), from Anatolia (Turkey) by way of the Mediterranean Sea and the Danube River.

It's easy to imagine some continuity from the lifestyle of hunters in regions of relative abundance like river valleys, to that of transhumant shepherds. A bit more difficult to connect this lifestyle with that of nomadic pastoralism.

Although this bacterium later caused bubonic plague, in this wave the disease seems to have been pneumonic plague.