Egyptian civilization: the south rises.

By the end of the fourth millennium B.C., Egypt emerged as a large territorial state ruled by a royal dynasty through a network of administrative centers. Archaeological evidence of how settlements sprinkled along the Nile Valley coalesced into one of the world's first civilizations remains murky.

However, a review of sites dating to between 3000 B.C. and 4000 B.C. concludes that a culture located about 300 miles south of the Nile Delta mobilized Egypt's first state. Available evidence does not support theories that invaders from other regions, such as Nubia, founded Egyptian civilization, asserts Kathryn A. Bard, an archaeologist at Boston University.

Two independent cultures existed in Egypt during the fourth millennium B.C., Bard maintains: the Nagada culture in the south and the Maada culture in the north. Most evidence of the Nagada culture comes from large cemeteries, where elaborate burials reflect the formation of elite social groups, Bard reports in the fall JOURNAL OF FIELD ARCHAEOLOGY.

Influences derived from Nagada grave styles, pottery types, and other artifacts show up in the first dynastic state, she says.

More well-preserved settlements exist for the Maada culture, but they contain much simpler burials and scant evidence of any social classes or lasting influence on later Egyptian civilization, according to Bard.

Only the Nagada people had access to gold and other valuable trade items with which they could obtain Mediterranean timber to construct a fleet of long-distance trading vessels, Bard contends. As trade expanded, Nagada groups moved north and eventually established a unified state, the Boston researcher theorizes.