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 (see “Building a Hellenized Society” in Chapter 5). 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. In 226 C.E. the Parthians were defeated by the Sassanids, a new dynasty in the area (see “The Sassanid Empire and Conflicts with Byzantium” in Chapter 8). When the Romans continued their attacks against this new enemy, the Sassanid king Shapur conquered the Roman legions of the emperor Valerian, whom he took prisoner. Shapur employed the captured Roman soldiers and engineers to build roads, bridges, dams, and canals, and their designs and methods were later used throughout the Sassanid empire.

Although warfare disrupted parts of western Asia, it did not stop trade that had prospered from Hellenistic times (see “The Growth of Trade and Commerce” in Chapter 5). Silk was still a major commodity from east to west, along with other luxury goods. In return the Romans traded glassware, precious gems, and slaves. The Parthians added exotic fruits, rare birds, rugs, and other products.

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 purchased local merchandise and wares imported by the Parthians. Merchants who made the voyage contended with wind, shoal waters, and pirates. Despite the dangers and discomforts, some hardy mariners pushed down the African coast and into the Indian Ocean, where they traded with equally hardy local sailors. Roman coins have been found in Sri Lanka and Vietnam, clear evidence of trade connections, although most likely no merchant traveled the entire distance.

The period of this contact coincided with the era of Han greatness in China (see “The Han Dynasty, 206 B.C.E.–220 C.E.” in Chapter 7). The Han emperor Wu encouraged trade by sea as well as by land, and during the reign of the Roman emperor Nerva (r. 96–98 C.E.), a later Han emperor sent an ambassador, Gan Ying, to make contact with the Roman Empire. Gan Ying made it as far as the Persian Gulf ports, where he heard about the Romans from Parthian sailors and reported back to his emperor that the Romans were wealthy, tall, and strikingly similar to the Chinese. His report became part of a group of accounts about the Romans and other “western” peoples that circulated widely among scholars and officials in Han China. Educated Romans did not have a corresponding interest in China. For them, China remained more of a mythical than a real place, and they never bothered to learn more about it.