Dunhuang was made a prefecture in 117 BCE by Emperor Han Wudi, and was a major point of interchange between China and the outside world during the Han and Tang dynasties. Located near the historic junction of the northern and southern Silk Roads, it was a town of military importance. Its name is mentioned as part of the homeland of the Yuezhi or "Rouzhi" 月氏 in the Shiji 史記, but this mention has also been identified with an unrelated toponym, Dunhong.