Test pits were excavated in several areas around the central mound to determine if the more-than-1-meter-thick layer of river stones (seen here in Test Pit 5) covered the entire mound. They did! And to a level that exceeded 1 meter. To complete this layer of rock would have been very labor intensive, would have taken a lengthy period of time, and the nomads would have been well organized–the closest river is some 15-20 kilometers away over the top of the mountain to the west.