YEARS ago one could buy at the Rand McNally map store a curio called “The Histomap of History.” Measuring about 12 inches wide and, when unfolded, about five feet long, it shows in bands of different colors and varying widths the concurrent rise and fall of empires and peoples over a period of 4,000 years. It begins in 2000 B.C., when the Egyptians are the dominant people, flanked by the Aegeans, Hittites, Amorites, Iranians, Indians, Huns, and Chinese. By 1000 B.C., the Aegeans have disappeared; the Egyptians have been narrowed to a thin river; the Hittites, after a long period of expansion, are on the verge of extinction; the Assyrians, who begin in 1400 B.C., have begun to dominate the flow of time, widening by 800 B.C. to the major force on the world-chart. And so on, through the varying fates of the Greeks, the Romans, the Goths, the Huns....