The transition from paleolithic to neolithic culture is not yet known; but we do know that a change of climate, which started in the Old Stone Age, continued in the New, and very gradually changed living conditions throughout the Near East. Libya remained rich in vineyards, olive trees, and cattle up to the end of the second millennium B.C.—a fact which may be surmised from records of booty brought back from there: by a Pharaoh of the First Dynasty;[40] by Sahure of the Fifth Dynasty (about 2475 B.C.), who listed 100,000 head of cattle and more than 200,000 each of asses, goats, and sheep;[41] and finally by Ramses III (about 1175 B.C.), who was still able to take away 3600 head of cattle, in addition to horses, asses, sheep, and goats.[42] At the opposite end of the Near East, in south-eastern Iran, Sir Aurel Stein was unable to round up a “minimum of local labour” to investigate the thickly dotted ruins of ancient settlements.[43] Nevertheless, progressive desiccation marked the period from perhaps 7000 B.C. onwards, turning the plateaux from grassland into steppe and, ultimately, into desert, and making the valleys of the great rivers inhabitable. When meadows and shrub lands began to emerge from the swamps and mudflats along the river courses, man descended from the highlands. Now the earliest inhabitants of the valleys were in possession of a considerable body of knowledge which the hunters of the Ice Age had lacked. And we do not know how the change from old to new, from the Old Stone Age to the New Stone Age, came about; for nowhere has a series of continuous remains covering the transition been _recognized_. I use this word advisedly, for we shall see in a moment that the change was of such a nature that its earliest consequences may well defy recognition. We know, however, that this change, like the later one with which we are more especially concerned, took place in the Near East.[44]