What archaeologists think of as the beginning of civilization (the rise of Sumeria, the Indus Valley Civilization, and Egypt between 3300 and 2900 BC) was the beginning of complex cities. As we explored in the final chapter on descending Treta Yuga, the concept of the Neolithic Revolution, when humanity was supposed to have made a great leap forward because of the confluence of such developments as agriculture, animal domestication, pottery, and the plow, appears not to hold together. Most, if not all, of the critical discoveries and developments had already been present for millennia.