Statement 1: Loulan disappeared in the war. After the 5th century A.D., the kingdom of Loulan began to weaken, the northern powers invaded, Loulan city was broken, and then abandoned. The evidence is Wang Changling's "Joining the Army": The yellow sand wears the golden armor for hundreds of battles, and if it is not broken, it will not be returned.
But these words can only explain the ambitions of the generals, but they can't express the disappearance of Loulan country, which can basically be ruled out; However, the word "Battle of Yellow Sand" can still give an important signal. At that time, the land at the foot of Loulan was sand, which was not suitable for water conservation.
Statement 2: Loulan declined due to drought and water shortage and ecological deterioration, and the upper reaches of the river were cut off and diverted, so people had to leave Loulan.
Statement 3: The disappearance of Loulan is related to the north-south migration of Lop Nur. Sven Hedin (Swedish explorer, 1900, the ancient city of Loulan was first discovered) thought that the period of north-south migration of Lop Nur was about 1500 years. More than 3,000 years ago, there lived a European ethnic tribe in Loulan area. Loulan once again entered a prosperous era more than 1500 years ago, which was directly related to the wandering of Lop Nur.
Statement 4: The disappearance of Loulan is related to the opening of the North Road of the Silk Road. After the opening of the Silk Road North Road through Hami (Yiwu) and Turpan, the ancient Silk Road Desert Road through Loulan was abandoned, and Loulan lost its former glory.