What is Lou LAN

Loulan: The king of Loulan was greedy for money, and repeatedly killed the Han envoy to the Western Regions, and later Fu Jiezi went to the Western Regions to kill the king. So "Loulan" often refers to the enemy of the border.

Tang Wang Changling "From the army" : "Qinghai long cloud dark snow mountain, the lonely city looking at Yumen Pass. Huangsha wears golden armor, and it will not return until Loulan is broken."

Tang Libai "plug down song" : "Would like to waist sword, straight to cut Loulan."