The Silk Road was an ancient network of trade routes that connected the East and West. It was central to cultural interaction between the regions for many centuries. The Silk Road refers to both the terrestrial and the maritime routes connecting East Asia and Southeast Asia with East Africa, West Asia and Southern Europe. The Silk Road derives its name from the lucrative trade in silk carried out along its length, beginning in the Han dynasty (207 BCE-220 CE). The Han dynasty expanded the Central Asian section of the trade routes around 114 BCE through the missions and explorations of the Chinese imperial envoy Zhang Qian. The Chinese took great interest in the safety of their trade products and extended the Great Wall of China to ensure the protection of the trade route. Trade on the Road played a significant role in the development of the civilizations of China, Korea, Japan, India, Iran, Afghanistan, Europe, the Horn of Africa and Arabia, opening long-distance political and economic relations between the civilizations. Though silk was the major trade item exported from China, many other goods were traded, as well as religions, syncretic philosophies, sciences, and technologies. Diseases, most notably plague, also spread along the Silk Road. In addition to economic trade, the Silk Road was a route for cultural trade among the civilizations along its network. Traders in ancient history included the Bactrians, Sogdians, Syrians, Jews, Arabs, Iranians, Turkmens, Chinese, Malays, Indians, Somalis, Greeks, Romans, Georgians, Armenians, and Azerbaijanis.