The expansion of trade during the pax Romana made the Roman Empire an economic as well as a political force in the provinces (see Map 6.2). Britain and Belgium became prime grain producers, with much of their harvests going to the armies of the Rhine, and Britain’s wool industry probably got its start under the Romans. Italy and southern Gaul produced huge quantities of wine, which was shipped in large pottery jugs wherever merchant vessels could carry it. Roman colonists introduced the olive to southern Spain and northern Africa, which soon produced most of the oil consumed in the western part of the empire. In the East, the olive oil production of Syrian farmers reached an all-time high, and Egypt produced tons of wheat that fed the Roman populace.

The growth of industry in the provinces was another striking development of this period. Cities in Gaul and Germany eclipsed the old Mediterranean manufacturing centers. Lyons in Gaul and later Cologne in Germany became the new centers of the glassmaking industry, and the cities of Gaul were nearly unrivaled in the manufacture of bronze and brass. The Romans took the manufacture of pottery to an advanced stage by introducing a wider range of vessels and making some of these on an industrial scale, in kilns that were large enough to fire tens of thousands of pots at once. The most prized pottery was terra sigillata, reddish decorated tableware with a glossy surface. Methods for making terra sigillata spread from Italy northward into Europe, often introduced by soldiers in the Roman army who had been trained in potterymaking in Italy. These craftsmen set up facilities to make roof tiles, amphoras, and dishes for their units, and local potters began to copy their styles and methods of manufacturing. Terra sigillata often portrayed Greco-Roman gods and heroes, so this pottery spread Mediterranean myths and stories. Aided by all this growth in trade and industry, Europe and western Asia were linked in ways they had not been before.

As the Romans drove farther eastward, they encountered the Parthians, who had established a kingdom in what is now Afghanistan and Iran in the Hellenistic period. In the second century, the Romans tried unsuccessfully to drive out the Parthians, who came to act as a link between Roman and Chinese merchants. Chinese merchants sold their wares to the Parthians, who then carried the goods overland to Mesopotamia or Egypt, from which they were shipped throughout the Roman Empire. Silk was a major commodity traded from the East to the West, along with other luxury goods. In return, the Romans traded glassware, precious gems, and slaves. The pax Romana was also an era of maritime trade, and Roman ships sailed from Egyptian ports to the mouth of the Indus River, where they traded local merchandise and wares imported by the Parthians.