We tend to forget now but the Silk Road, as a kind of artery between great civilizations, dominated the world's destiny for much of humankind's collective experience. And, of course, the world has largely remembered the region from the perspective of those great chronicling cultures: China, India, Europe, the Mideast, and the like. In their nether zones sat the limitless tract of steppe lands from whose bourne emerged not just rich caravans of trade but wave after wave of warrior tribes on horseback. For upwards of a couple of millenia from the Scythians to Attila to Genghis Khan and the Ottomans, they disturbed the settled order of things, sometimes even established their own order, but chiefly forged their achievements through predation on the older, more recognized societies.