Dayuan (or Tayuan; ) is the Chinese exonym for a country that existed in Ferghana valley in Central Asia, described in the Chinese historical works of "Records of the Grand Historian" and the "Book of Han". It is mentioned in the accounts of the famous Chinese explorer Zhang Qian in 130 BCE and the numerous embassies that followed him into Central Asia. The country of Dayuan is generally accepted as relating to the Ferghana Valley, controlled by the Greek polis Alexandria Eschate (modern Khujand, Tajikistan).