In the first aspect, Loulan is a traffic fortress in the northwest. If you want to attack the Huns, you must first go to Loulan. Loulan is located in the northwest fortress. If the Huns attack, the Han Dynasty must go to Loulan first, and then attack the Huns. So Loulan at this time is similar to Shanhaiguan and has become a geographical landmark. For example, it is said that Shanhaiguan was a wilderness in the eyes of the ancients, and so was Loulan at this time. When it comes to Loulan, just hit the Huns. Loulan is located in the fortress, so trade also goes through Loulan, which also promotes the economic development of Loulan.
In the second aspect, Loulan did not bow to the Han Dynasty. Loulan was actually a small country vacillating between Han Dynasty and Xiongnu. Therefore, for the Han Dynasty, sometimes it is necessary not only to resist the Xiongnu, but also to prevent Loulan from helping the Xiongnu and even invading the frontier. Because Loulan had no clear attitude before the Han Dynasty, he was also hated.
In the third aspect, Loulan generally refers to the nomadic people in the north. In ancient times, when materials were scarce, they often harassed people in border areas. Nomads in the north often disturb the frontier and bring war and disaster, so aspiring scholars want to pacify the frontier and show their ambitions.
Based on the above reasons, Loulan has become synonymous with northern nomadic people in ancient poetry, so the reference to Loulan in poetry is often regarded as the node to win the war, rather than simply referring to the country and place names. The above is my opinion on this matter, and I hope to adopt it.