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Chinese foreign trade began as early as the Western Han dynasty (206 BCE-9 CE), when the famous "Silk Road" through Central Asia was pioneered by Chinese envoys. During later dynasties, Chinese ships traded throughout maritime Asia, reaching as far as the African coast, while caravans extended trade contacts in Central Asia and into the Middle East. Foreign trade was never a major economic activity, however, and Chinese emperors considered the country to be entirely self-sufficient. During parts of the Ming (1368–1644) and Qing (1644–1911) dynasties, trade was officially discouraged. In the mid-eighteenth century, the government restricted sea trade by setting up the Canton System.