Western Regions

— From the historical point of view, trade and expansion in this period began as a reaction to the barbarian threat of the Hsiung-nu on the northern and northwestern frontiers, and ended not only in the inclusion of various barbarian groups into the empire, such as the Southern Hsiung-nu, the Ch’iang, the Wu-huan, and the Southwestern barbarians, but also in the Sinicization of them to greater and lesser degrees. In between, China also expanded to the Western Regions and Central Asia, and even established trading relations, directly or indirectly, with countries farther west.