Mediterranean route, probably by middlemen through Byblos, is more likely, as evidenced by the presence of Byblian objects in Egypt. The fact that so many Gerzean sites are at the mouths of wadis that lead to the Red Sea may indicate some amount of trade via the Red Sea (though Byblian trade potentially could have crossed the Sinai and then taken the Red Sea). Also, it is considered unlikely that something so complicated as recessed panel architecture could have worked its way into Egypt by proxy, and at least a small contingent of migrants is often suspected. Despite this evidence of foreign influence, Egyptologists generally agree that the Gerzean Culture is still predominantly indigenous to Egypt. Protodynastic Period (Naqada III) The Naqada III period, from about 3200 to 3000 BC, is generally taken to be identical with the Protodynastic period, during which Egypt was unified. Naqada III is notable for being the first era with hieroglyphs (though this is disputed by some), the first regular use of serekhs, the first irrigation, and the first appearance of royal cemeteries. The relatively affluent Maadi suburb of Cairo is built over the original Naqada stronghold. Bioarchaeologist Nancy Lovell, had stated that there is a sufficient body of morphological evidence to indicate that ancient southern Egyptians had physical characteristics "within the range of variation" of both ancient and modern indigenous peoples in the Sahara and tropical Africa. She summarised that "In general, the inhabitants of Upper Egypt and Nubia had the greatest biological affinity to people of the Sahara and more southerly areas" but exhibited local variation in an African context. Timeline Late Paleolithic, from 40th millennium BC Aterian tool-making Semi-permanent dwellings in Wadi Halfa Tools made from animal bones, hematite, and other stones Neolithic, from 11th millennium BC c. 10,500 BC: Wild grain harvesting along the Nile, grain-grinding culture creates world's earliest stone sickle blades roughly at end of Pleistocene c. 8000 BC: Migration of peoples to the Nile, developing a more centralized society and settled agricultural economy c. 7500 BC: Importing animals from Asia to Sahara c. 7000 BC: Agriculture—animal and cereal—in East Sahara c. 7000 BC: in Nabta Playa deep year-round water wells dug, and large organized settlements designed in planned arrangements c. 6000 BC: Rudimentary ships (rowed, single-sailed) depicted in Egyptian rock art c. 5500 BC: Stone-roofed subterranean chambers and other subterranean complexes in Nabta Playa containing buried sacrificed cattle