Long-distance trade played a major role in the cultural, religious, and artistic exchanges that took place between the major centers of civilization in Europe and Asia during antiquity. Some of these trade routes had been in use for centuries, but by the beginning of the first century A.D., merchants, diplomats, and travelers could (in theory) cross the ancient world from Britain and Spain in the west to China and Japan in the east. The trade routes served principally to transfer raw materials, foodstuffs, and luxury goods from areas with surpluses to others where they were in short supply. Some areas had a monopoly on certain materials or goods. China, for example, supplied West Asia and the Mediterranean world with silk, while spices were obtained principally from South Asia. These goods were transported over vast distances— either by pack animals overland or by seagoing ships—along the Silk and Spice Routes, which were the main arteries of contact between the various ancient empires of the Old World. Another important trade route, known as the Incense Route, was controlled by the Arabs, who brought frankincense and myrrh by camel caravan from South Arabia.
Cities along these trade routes grew rich providing services to merchants and acting as international marketplaces. Some, like Palmyra and Petra on the fringes of the Syrian Desert, flourished mainly as centers of trade supplying merchant caravans and policing the trade routes. They also became cultural and artistic centers, where peoples of different ethnic and cultural backgrounds could meet and intermingle.
The trade routes were the communications highways of the ancient world. New inventions, religious beliefs, artistic styles, languages, and social customs, as well as goods and raw materials, were transmitted by people moving from one place to another to conduct business. These connections are reflected, for example, in the sculptural styles of Gandhara (modern-day Pakistan and northern India) and Gaul (modern-day France), both influenced by the Hellenistic styles popularized by the Romans.