Even before Han's expansion into Central Asia, diplomat Zhang Qian's travels from 139 to 125 BC had established Chinese contacts with many surrounding civilizations. Zhang encountered Dayuan (Fergana), Kangju (Sogdiana), and Daxia (Bactria, formerly the Greco-Bactrian Kingdom); he also gathered information on Shendu (Indus River valley of North India) and Anxi (the Parthian Empire). All of these countries eventually received Han embassies. These connections marked the beginning of the Silk Road trade network that extended to the Roman Empire, bringing Han items like silk to Rome and Roman goods such as glasswares to China. From roughly 115 to 60 BC, Han forces fought the Xiongnu over control of the oasis city-states in the Tarim Basin. Han was eventually victorious and established the Protectorate of the Western Regions in 60 BC, which dealt with the region's defense and foreign affairs. The Han also expanded southward. The naval conquest of Nanyue in 111 BC expanded the Han realm into what are now modern Guangdong, Guangxi, and northern Vietnam. Yunnan was brought into the Han realm with the conquest of the Dian Kingdom in 109 BC, followed by parts of the Korean Peninsula with the colonial establishments of Xuantu Commandery and Lelang Commandery in 108 BC. In China's first known nationwide census taken in 2 AD, the population was registered as having 57,671,400 individuals in 12,366,470 households.