Different authorities define the borders and number of Eurasia’s subregions differently. Subregional maps of Eurasia are all generally similar, however, since the subregions correspond closely to geographical realities. The major subregions are: the Intermontaine Desert and Oasis Belt; the Trans-Eurasian Steppe Belt; China; the Mediterranean; the Middle East; South Asia; Northeast Asia; Northern Europe; Mainland Southeast Asia; Island Southeast Asia; the Boreal Forest; and the Arctic Littoral. (Although the latter two occupy a significant fraction of the Eurasian landmass, they historically played little role in long-distance travel and trade, and so they are generally left out of this discussion.)
Intermontaine Desert and Oasis Belt
The zone of the Silk Road itself, this broad belt of oasis-punctuated deserts extends across Central Asia from northwestern China, to the Caspian and Black Seas, and on to the Middle East. The zone is bounded on the north and south by mountains, but can be traversed with only afew mountain ranges to cross along the way. Features including a high, dry terrain, infrequent and irregular water supplies, absent or scarce forage for caravan animals, and other difficulties made this zone passable only to highly skilled Silk Road caravaneers. Travel was made possible by people whose local knowledge and experience could enable them to survive and deliver their cargo safely from stage to stage.
The most clearly defined segment of the Silk Road was that leading northwest from Chang’an through the Gansu Corridor. This segment passed through Lanzhou, Wuxi, Dunhuang, and Yumen (the famous Jade Gate ofantiquity) and thus to the deserts and oases of Central Asia. Bounded by mountains to the south, and by the western Gobi Desert to the north(and de.ned as well by the western stretches of the Great Wall of China), the corridor forms in effect a narrow funnel through which all trade passed on the Silk Road into and out of China.
Beyond the Jade Gate, the Silk Road opens into a number of alternative trails. One possibility is to go northwest through Hami, Turfan and Urumqi, traveling north of the Tian (Heavenly) Mountains through Dzungaria, then on to Kokand and Tashkent in the Ferghana Valley. Another route leads southwest from the Jade Gate and soon poses a choice, whether to skirt the fierce Taklamakan Desert along the northern or along the southern rim of the Tarim Basin. The southern route via Khotan and Yarkand was perhaps marginally easier. Either way,the route converges again at Kashgar, at the foot of the Pamir Mountains, where the route crosses the Turugart Pass leading to Kokand and points west. Still another branch route took a more southerly pass through the Pamirs, and went on to Bactria leading to routes through Afghanistan and on to northwestern India.
Of the northern routes that converged in the Ferghana Valley, several routes led onward to Samark and and Merv. Divergent trails led north of the Caspian to the Russian trade routes up the Volga and the Don; straight west, skirting the southern coast of the Caspian and Black Seas toward Byzantium; or south, through Herat and Persepolis toward Babylon, Damascus and Tyre. The Silk Road had not one western terminus, but many.
The terrain of the Silk Road was difficult, the possible routes were numerous and complex, and the dangers of the journey were deadly serious.
What made the journey possible at all, besides the techniques of caravan travel and the expertise of the caravaneers, was the existence of substantial oases across Central Asia. These islands of greenery, watered by rivers and springs, ranged in extent from a few square miles to hundreds of square miles, but even the largest were isolated by huge expanses of surrounding deserts. In mapping routes of the Silk Road, one can easily imagine the terrors and hardships of the desert; one can imagine also the joys of arriving at oases like Dunhuang, Hami or Herat, filled with sweet water and fresh fruit to refresh the traveler and provide respite before the journey’s next stage.