Externally, the Han dynasty neutralized the threat posed by the nomadic Xiongnu following a series of wars.[14] The boundaries of China was extended into what is modern-day western Xinjiang, South Korea (near modern Seoul), and Vietnam (around modern Huế).[15] The Silk Road emerged as a major route that connected the East and the West after the Han diplomat Zhang Qian established contact with the numerous Central Asian tribes and states, thus facilitating commerce and cultural exchanges.[16]