A fertile basin located east of the Tianshan Mountain range 天山 and surrounded by high mountain chains that today are part of Kirgizstan while the basin belongs to Uzbekistan, Chinese: Feirganna 費爾干納盆地. During the Han period the Ferghana area was famous for its "heavenly horses", and Emperor Han Wudi 漢武帝 sent Zhang Qian 張騫 as an envoy to establish relationships with the Dayuan 大宛 empire. After passing Shule (Kashgar) traders of the Silkroad had to pass the Ferghana Basin on their way to Central Asia.