The Silk Road was not a single road but a network of caravan routes linking China to the Mediterranean across Central Asia, and its importance as a cultural transmission belt has arguably been underestimated compared to its more discussed economic function.

The routes functioned across roughly two millennia, from the Han Dynasty's active diplomacy with Central Asian polities beginning in the 2nd century BC through the Mongol period when the Pax Mongolica briefly made overland travel relatively safe. The Chinese end sought horses — the famous 'blood-sweating' Ferghana horses that were superior to Central Asian breeds — and the western end sought silk, which remained a luxury good of extraordinary value in Roman and Byzantine markets.

What traveled along these routes beyond silk, horses, and spices is most historically significant: Buddhism came from India to China along these routes (and with it a massive translation project and artistic tradition); Islam spread across Central Asia by the same paths; the Black Death traveled from Central Asian rodent populations to Europe along the caravan routes in the 14th century.

The oasis cities of Central Asia — Samarkand, Bukhara, Dunhuang, Merv — were not mere waypoints but cosmopolitan cultural centers where Sogdian, Chinese, Indian, and Iranian traditions interacted. The Sogdian merchants who dominated Central Asian trade from the 4th to 8th centuries AD were multilingual, long-distance traders whose letters (discovered frozen in a watchtower in the Gansu Corridor) give a vivid picture of commercial and personal life.