We don't know exactly - only that they were.
We have nothing to go by but speculation on how these nomadic bands grew in numbers and in ferocity and over what span of time.4 But by the fifth millennium B.C.E., or about seven thousand years ago, we begin to find evidence of what Mellaart calls a pattern of disruption of the old Neolithic cultures in the Near East.5 Archaeological remains indicate clear signs of stress by this time in many territories. There is evidence of invasions, natural catastrophes, and sometimes both, causing large-scale destruction and dislocation. In many areas the old painted pottery traditions disappear. Bit by devastating bit, a period of cultural regression and stagnation sets in. Finally, during this time of mounting chaos the development of civilization comes to a standstill. As Mellaart writes, it will be another two thousand years before the civilizations of Sumer and Egypt emerge.6
Eisler, Riane. The Chalice and the Blade (p. 84). HarperCollins. Kindle Edition.
In contrast with the peoples of Old Europe as well as those of Mesopotamia, who worshipped a life-giving goddess that brought abundance, law, art, and beauty both the Kurgans and the ancient Hebrews worshipped a god of war and mountains, one who had no balancing female consort like that of the goddess. These invaders glorified in the death and destruction that they brought in the name of their god (Jehovah or Yahweh for the Hebrews), and in the case of the Kurgans, they actually paid devotion to their swords.
The one thing they all had in common was a dominator model of social organization: a social system in which male dominance, male violence, and a generally hierarchic and authoritarian social structure was the norm. Another commonality was that, in contrast to the societies that laid the foundations for Western civilization, the way they characteristically acquired material wealth was not by developing technologies of production, but through ever more effective technologies of destruction.
Eisler, Riane. The Chalice and the Blade (p. 86). HarperCollins. Kindle Edition.
