Editing Geographical exploration (section)

===Chinese exploration of Central Asia===
During the 2nd century BC, the [[Han dynasty]] explored much of the Eastern Northern Hemisphere. Starting in 139 BC, the Han diplomat [[Zhang Qian]] traveled west in an unsuccessful attempt to secure an alliance with the Da [[Yuezhi]] against the [[Xiongnu]] (the Yuezhi had been evicted from [[Gansu]] by the Xiongnu in 177 BC); however, Zhang's travels discovered entire countries which the Chinese were unaware of, including the [[Hellenistic civilization|remnants of the conquests]] of [[Alexander the Great]] (r. 336–323 BC).{{sfnm|di Cosmo|2002|1pp=247–249|Yü|1986|2p=407|Torday|1997|3p=104|4a1=Morton|4a2=Lewis|4y=2005|4pp=54–55}} When Zhang returned to China in 125 BC, he reported on his visits to [[Dayuan]] ([[Fergana]]), [[Kangju]] ([[Sogdia]]), and [[Daxia]] ([[Bactria]], formerly the [[Greco-Bactrian Kingdom]] which had just been subjugated by the Da Yuezhi).{{sfn|Torday|1997|pp=105–106}} Zhang described Dayuan and Daxia as agricultural and urban countries like China, and although he did not venture there, described Shendu (the [[Indus River]] valley of Northwestern India) and Anxi ([[Parthian Empire|Parthian]] territories) further west.{{sfn|Torday|1997|pp=108–112}}