The term ¡Western regions¡, as it was understood in the Han Dynasty, meant the land west of Yumen Pass in Gansu Province, as well as
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the land further away in Central Asia. When Emperor Han Wu-di planned to attack the Huns he wanted the Ephthalites in the Western Regions 
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to help him. Therefore he tried to recruit a man who could go to the land of the Ephthalites, and Zhang Qian volunteered. In 138 BC, Zhang Qian
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set out on the trip with an entourage of more than 100 people. Thus started the frequent official exchanges  between China and countries in mid-
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dle and central Asia.