The position of Arabia, between the valleys of the Nile and the Euphrates and Tigris, where agriculture and civilisation came into bloom at an early period, and which were the oldest seats of trade and industry, brought the Arab tribes who wandered along the borders of these river valleys into connection with Egypt and Babylon. Barter had to supply all that could not be obtained by freebooting. The nomads required corn, implements, and weapons; Egypt and Babylon were in need of horses, sheep, goats, and camels. The Arabians, therefore, could exchange their animals for corn, weapons, and implements, and supply the industry of Babylon and Egypt with a part of the necessary raw products, more especially skins and wool. The tradition of the Hebrews represents Abraham as going to Egypt, and the sons of Jacob buy corn in Egypt when "there was a famine in the land." On the other hand, Egypt, as has been already remarked, had already, under Snefru, the predecessor of Chufu, _i.e._ about the year 3000 B.C., fixed herself in the peninsula of Sinai, and when, a thousand years later, nomad tribes of the north-west of Arabia obtained the supremacy in the valley of the Nile, and maintained it for centuries (p. 123), their supremacy could only develop further the trade between Egypt and the Arabs, between the ruling tribe in Egypt and their kinsmen at home, and thus the contact with the civilisation of Egypt and Babylonia was not without effect on the Arabs. This contact increased their wants, and therefore increased their trading intercourse. The Arabs could offer not merely the products of their herds, they could exchange the costly spices and perfumes from the southern coast of their land with each other, and so convey them to the Egyptians and Babylonians. The Hebrew Scriptures make Keturah, _i.e._ "Incense," the wife of Abraham, and from this connection spring the Midianites and the Dedanites; to Esau, the son of Isaac, the progenitor of the Edomites, they give a wife of the name of Basmath, _i.e._ "Perfume,"[446] and in the twentieth century B.C., according to their reckoning, we find a caravan of Ishmaelites, with camels, carrying spices, balsam, and ladanum, and Midianites going for purposes of trade to Egypt.