Hou Junji
Although the Silk Road from China to Europe and the Western World was initially formulated during the reign of Emperor Wu (141–87 BC) during the Han, it was reopened by the Tang in 639 when Hou Junji ( 643) conquered the West, and remained open for almost four decades. It was closed after the Tibetans captured it in 678, but in 699, during Empress Wu's period, the Silk Road reopened when the Tang reconquered the Four Garrisons of Anxi originally installed in 640, once again connecting China directly to the West for land-based trade.