Just like the immortal poem of the great poet Wang Changling in "Seven Books on the Art of War": The yellow sand wears golden armor for hundreds of battles, and the broken loulan does not return. Other frontier poets, such as Gao Shi, have poems such as "Horseshoe Crossing the Moon Hole, Sword Pointing at Loulan", and Cen Can has poems such as "Xiongnu Drive Wanma and Take Loulan King".
However, Loulan in history had been destroyed as early as the Northern and Southern Dynasties, and it had been destroyed for hundreds of years when the Tang Dynasty was established. The enemies of the Tang Dynasty who fought against the Tang Dynasty in the Western Regions were Turks at first, and then Tubo. So why do poets in the Tang Dynasty take "Loulan" as their enemy when writing poems?
Loulan is an ancient country in the western regions with a long history. It is located on the Silk Road and is the hub of East-West trade, so it is a relatively powerful one among the countries in the western regions. Loulan flourished, sandwiched between the Han Dynasty and Xiongnu, with the first mouse at both ends, pleasing both sides, and more often favoring Xiongnu.
During the period of Emperor Wu of the Han Dynasty, even the Huns were beaten out of the water, and Loulan was naturally unable to resist. Emperor Wu of the Han Dynasty once sent troops to the Western Expedition, captured King Loulan alive and forced Loulan to submit to the Han Dynasty. But after a while, Loulan rebelled again.
Emperor Zhao of the Han Dynasty arrived. In view of the capriciousness of Loulan, Huo Guang sent ten warriors headed by Fu Jiezi to kill King Loulan directly in the name of giving Loulan gold coins, and made his brother king. Since then, Loulan has been completely controlled.
This incident is unprecedented. Another king was killed in the enemy's capital. At that time, Fu Jiezi held the head of King Loulan and said, "The king committed the crime of the Han Dynasty, and the son of heaven sent me to punish the king, so that the former prince could settle down in the Han Dynasty.". When the Han soldiers arrive, they dare not move, or they will die!
It means that King Loulan failed Han, so the son of heaven sent me to kill King Loulan, and now the prince who used to be a Korean hostage is King Loulan. Han army is outside. If you want to move, destroy your country!
Such a great achievement, Fu Jiezi's great success in the Western Regions, has also become a common allusion for later poets. Even Li Bai, a great poet with graceful demeanor, can't avoid familiarity. He once wrote the poem "I would like to cut Loulan with a machete", and another great poet Du Fu also wrote the poem "It is too late to die, but Loulan has not been cut back".
At that time, the Tang Dynasty often fought against Turks and Tubo in the former site of Loulan. These poets lamented the history and remembered Fu Jiezi's great achievements, so they naturally chose the allusion of "Chopping Loulan".
Another point is that, compared with other countries in the Western Region, Xiongnu, Qiuci and Yueshi are all closed-door pronunciations, which are not suitable for the generosity and heroism of frontier poets, while Loulan is closed first and then opened, which is gentle and suitable for rhyme, so it will also be used.