Menes was followed by six dynasties of kings, who reigned in all 1478 years. The tombs of the two first dynasties have been found at Abydos. Menes himself was buried on the edge of the desert near Negada, about twenty miles to the north of Thebes. His sepulchre was built in rectangular form, of crude bricks, and filled with numerous chambers, in the innermost and largest of which the corpse of the king was laid. Then wood was heaped about the walls and the whole set on fire, so that the royal body and the objects that were buried with it were half consumed by the heat. The mode of burial was peculiar to Babylonia. Here, in an alluvial plain, where stone was not procurable, and where the cemeteries of the dead adjoined the houses of the living, brick was needful instead of stone, and sanitary considerations made cremation necessary. But in the desert of Egypt, at the foot of rocky cliffs, such customs were out of place; their existence can be explained only by their importation from abroad. The use of seal-cylinders of Babylonian pattern, and of clay as a writing material, in the age of Menes and his successors, confirms the conclusion to which the mode of burial points. The culture of Pharaonic Egypt must have been derived from the banks of the Euphrates. That Menes should have been buried at Negada, and not, like the rest of his dynasty, in the sacred necropolis of his mother-city, is strange. But we are told that he was slain by a hippopotamus, the Egyptian symbol of a foe. It may be, therefore, that he fell fighting in battle, and that his sepulchre was erected near the scene of his death. However that may be, the other monarchs of the first two dynasties were entombed at Abydos, The mode of burial was the same as in the case of Menes. The objects found in the tombs of Menes and his successors prove that the culture of Egypt was already far advanced. The hieroglyphic system of writing was fully developed, tools and weapons of bronze were used in large quantities, the hardest stones of the Red Sea coast were carved into exquisitely-shaped vases, plaques of ivory were engraved with high artistic finish, and even obsidian was worked into vases by means of the lathe. As the nearest source of obsidian to Egypt that is known are the islands of Santorin and Melos in the Ægean Sea, there must have already been a maritime trade with the Greek seas. Art had already reached maturity; a small dog carved out of ivory and discovered in the tomb of Menes is equal to the best work of later days. Finally, the titles assumed by the Pharaohs are already placed above the double name of the king, and the symbols employed to denote them are the same as those which continued in use down to the end of the Egyptian monarchy.