Reasons for the disappearance of Loulan

Xinjiang is an attractive place for adventure tourists. This mysterious ancient city, known as "Pompeii in the desert", is Loulan, an ancient country in the western regions.

Guloulan is located in the west bank of Lop Nur, Ruoqiang County, Bayinguoleng Mongolian Autonomous Prefecture, Xinjiang, and is one of the most desolate areas in Xinjiang. How fascinating the long history and fables here are; It mysteriously disappeared on the earth and unexpectedly appeared, which aroused the interest of many people-many Chinese and foreign tourists and explorers took pains to travel westward along the Silk Road to witness this famous historical and cultural city-Guloulan. 1979 1 Peng Zeng, a late scientist from China, set out from the north bank of Peacock River and walked across the desert to visit the Loulan site.

Loulan is a hub on the Silk Road and an important center of Sino-Western trade in history. Sima Qian once recorded in "Historical Records": "Loulan, Gushi City has a city wall, near salt." This is the first record of Loulan City in literature. In the Western Han Dynasty, the total population of Loulan was14,000, with business trips, lively markets, clean streets and magnificent Buddhist temples and pagodas. However, the Huns were powerful at that time, and Loulan was once controlled by them. They attacked and killed envoys of the Han Dynasty and robbed businessmen. Emperor Wu of the Han Dynasty sent troops to break it, captured King Loulan alive and forced him to attach himself to the Han Dynasty. However, Loulan listened to the treachery of the Huns and stopped and killed Han officials many times. In the fourth year of Han Yuanfeng (77 BC), General Huo Guang sent Fu Jiezi to take some warriors to Loulan, designed and killed the king of Loulan, made a taste of his younger brother, changed his name to Shanshan, and moved his capital to the south. However, the management of Loulan was not relaxed in Han Dynasty, and Loulan was still very prosperous.

After the Eastern Jin Dynasty, the Central Plains became independent, and wars continued, and Loulan gradually lost contact with the Central Plains. The Central Plains was strong in the Tang Dynasty, and the Tang Dynasty and Tubo met many times in Loulan. "Tianshan five In the snow, smallpox is only cold. Spring can only be imagined in the flute "Folding Willow", but it has never been seen in reality. Sean Xiao followed the golden drum, and went to bed at night to suppress the jade saddle. It turned out that he put his sword under his waist and cut Loulan straight. " (Xia Sai Qu by Li Bai). "Qinghai Yunchang Snow Mountain is dark, and the lonely city looks at Yumenguan. The yellow sand wears golden armor in hundreds of battles, and the loulan is not returned. " (Wang Changling's Joining the Army) It can be seen that Loulan was still an important town in the Tang Dynasty. However, I don't know when this bustling town mysteriously disappeared. Where is the ancient country of Loulan? It has become a mystery that people have speculated for centuries.

1900 In March, Sven Hedin, a famous Swedish explorer, led an expedition to Xinjiang. They trudged in the desert. Aikedi, a Uighur from China, was looking for the lost iron axe when he came back from the original road. He met a desert gale and accidentally found an old castle under the sand. He told the liar about this discovery. The following year, Swing Harding arrived at this mysterious castle and excavated many cultural relics. After textual research, it is concluded that this ancient city is the long-lost ancient city of Loulan.

The reappearance of Loulan City has attracted explorers from all over the world to explore and find treasures. British Hungarian Stein, American Hun Qiandun and Japanese Orange Ruichao successively arrived at this "site of an ancient city with highly developed culture" and took away a number of important cultural relics.

Loulan City was discovered from under the sand dunes, but a bigger mystery puzzled the explorers: Why did Loulan City disappear for a long time, the oasis became a desert and Gobi, and the sand was buried in the city?

1878, Russian explorer Poole Geval visited Lop Nur and found that the location of Lop Nur marked on the map of China was wrong. That's not at the southern foot of Kuruktag Mountain, but at the foot of Altun Mountain. At that time, Lop Nur, bathed by Poole Gerwar, was full of waves and wild birds, but now it has become a desert and salt marsh. In other words, Lop Nur is a flowing lake, and its actual location is 2 degrees south of the map.

Poole Gerwal partially solved the mystery. 1979 and 1980, Xinjiang scientists made many detailed investigations on it, and finally uncovered the mystery of "Pompeii in the sand" buried by sandstorms for more than 1600 years, making people see its true colors-

The exact geographical location of the ancient city of Loulan is 89 degrees 55 minutes and 22 seconds east longitude and 40 degrees 29 minutes and 55 seconds north latitude. Covering area108,000 square meters. The remaining walls in the east and west of the city are about 4 meters high and 8 meters wide. The city wall is rammed with loess; The courtyard walls of residential areas are made of mud that binds reeds into bundles or weaves wickers. All the wooden houses, the pillars of Hu Yangmu, and the doors and windows of the house are still clearly identifiable; There is a unique tulou in the city center, with a wall thickness of 1. 1 m and a residual height of 2 m, which faces south and seems to be the residence of the ruler of Guloulan. The mound in the east of the city turned out to be a pagoda for residents to worship Buddha.

How can Lop Nur wander? Scientists believe that apart from the factors of crustal activity, the biggest reason is the accumulation of a lot of sediment in the river bed. Sediments from Tarim River and Peacock River gather at the mouth of Lop Nur. Over time, more and more sediment accumulated and blocked the river. Tarim River and Peacock River flow to low-lying areas in another way, forming new lakes. In the hot climate, the old lake gradually evaporated and became a desert. Water is the source of all life in Loulan City. Lop Nur moved northward, making Loulan City thirsty, trees dying, and all citizens abandoned the city, leaving a dead city. In the raging desert storm, Loulan was finally annihilated by sand dunes.

The disappearance of Loulan is also related to people destroying the ecological balance of nature. Loulan is located on the main road of the Silk Road. Nomads such as Han and Xiongnu often provoke wars on the land of Loulan. Over-cultivation for the benefit of the country has seriously damaged water conservancy facilities and good vegetation: "After the third century A.D., the bed of the lower reaches of the Tarim River, which flowed into Lop Nur, was blocked by wind and sand, and now it is diverted to the south in the southeast of Yuli, resulting in Loulan's" barren city "and" the country is empty for a long time, and the city is barren. "

Lop Nur was once the largest lake in the arid area of northwest China, with a water surface area of10.2 million square kilometers, which still reached 500 square kilometers at the beginning of last century. At that time, Loulan people built an ancient city of Loulan with 65,438+10,000 square meters beside Lop Nur, but it finally dried up at 1972. What caused Lop Nur, once rich in water and fish, to become a vast desert? What caused the ancient city of Loulan, the crossroads of the Silk Road, to become a deserted desert Gobi? This has always been a scientific mystery.

The scientific investigation team of environmental drilling in Lop Nur, China Academy of Sciences conducted a comprehensive and systematic environmental scientific investigation in Lop Nur. According to preliminary inference, with the rapid uplift of the Qinghai-Tibet Plateau 70,000 to 80,000 years ago, Lop Nur moved from south to north, and the drought gradually intensified, eventually leading to the drying up of the whole lake. This explanation is obviously unsatisfactory. Professor Zhou Kunshu from the Institute of Geology and Geophysics, China Academy of Sciences thinks that the reasons for Lop Nur's drying up are very complicated. This is not only a global issue, but also a regional issue. Besides natural reasons, there are also human factors. About 10 thousand years ago, the earth's environment changed unprecedentedly, that is, from the dry and cold environment in the last glacial period to the humid environment in the post-glacial period. Taking this as an opportunity, human culture also entered the Neolithic Age from the Paleolithic Age. Ten thousand years later, the geological environment has undergone three major stages of change. The warming period is about 10000 to 8000 years ago, the high temperature period is about 8000 to 3000 years ago, and the cooling period is about 3000 years ago. These three environmental pattern changes have been confirmed by paleoenvironmental studies of geology, biology, chemistry and physics, but the time of dividing the three phases is slightly different due to different methods, places or research objects. This change of environment and climate has planned the scope and mode of human activities.

Take Loulan as an example. Humans set foot here in the Neolithic Age, and the population here was prosperous in the Bronze Age. At this time, it is just in the high temperature period, and the lake in Lop Nur is vast and the environment is suitable. However, after entering the cooling zone, the water and soil environment becomes worse, rivers decrease, lakes decrease and deserts expand. About 2000 years ago, the drought intensified, which was manifested by glacier transgression, loess accumulation, lake swamp disappearance and regression in the vast area of northern China.

The ancient city of Loulan disappeared from around A.D. to the 4th century (from Han Dynasty to Northern Wei Dynasty in the Central Plains), which was a period of intensified drought. In fact, during this drought, not only the ancient city of Loulan died, but also Niya, Karadun, Milan, Nyrang, Khan and Wantong cities died successively due to the expansion of the desert.

The disappearance of the ancient city of Loulan occurred in the north of China, even in the context of the world drought. It is not an isolated space, but because Loulan is located in the arid inland, the changes of humanities and natural environment here are more significant. Besides global climate change, the uplift of the Qinghai-Tibet Plateau is the most important reason in the region. 70,000-80,000 years ago, the Qinghai-Tibet Plateau rose rapidly. This uplift plays a decisive role in the climate of northwest China. Lop Nur is located in the northwest inland of East Asia. Warm and humid air currents from the Pacific Ocean and the Indian Ocean rarely arrive here every year.

When the global climate changes, drought, desertification and Gobi have begun to appear in the whole western East Asia. During this period, Lop Nur began to move from south to north. About 70 thousand years ago, the lake dropped sharply to the bottom.

Among regional factors, another point must be pointed out. According to the remote sensing data, a major landslide occurred in the upper reaches of Peacock River. Landslides blocked the entire channel of Peacock River, resulting in water cut-off in Lop Nur. I don't know the specific time of this landslide, and whether it happened before Lop Nur dried up remains to be studied. It can be said that human activities have a greater and greater impact on the drying up of Lop Nur. Water and trees are the key to the survival of wasteland oasis. The ancient city of Loulan was built in the downstream delta of Peacock River, where the water system was developed at that time, and the prosperous Hu Yangshu was once its capital. At that time, Loulan people built Loulan ancient city with an area of 6,543,800 square meters near Lop Nur. They cut down many trees and reeds, which will undoubtedly have a negative impact on the environment.

During this period, the intensification of human activities, the change of water system and the destruction of war have further deteriorated the fragile ecological environment. The dense "male roots and residual limbs" on the cemetery of Xiaohe No.5 show that Loulan people had already felt the crisis of tribal survival and had to pray for reproductive worship to protect their children and grandchildren. However, they cut down a large number of already scarce trees, which worsened the local environment.

The final drying up of Lop Nur is related to the over-exploitation of the upper reaches of Tarim River after our liberation. When we transferred a lot of water in the upper reaches of Tarim River, the water in Tarim River could not make ends meet, and the water in the lower reaches was cut off. This can be confirmed by the interruption of the Yellow River. Lop Nur also began to shrink rapidly and eventually died out because there was no water source. When the ancient city of Loulan is mentioned, people will think of the Swedish explorer Sven Hedin, because he first announced the existence of the ancient city of Loulan in 190 1.

On March 28th, 1900, Swedish explorer Sven Hedin was inspecting the Rob Desert. He hired Eldik, a donkey worker and guide, as a Uighur farmer, who lost his tools. On his way to Lop Nur, he came across an ancient site. When Sven Hedin heard about it, he immediately followed Eldik to this place and found that this ancient place was littered with beautiful wood carvings, fabrics and coins.

Sven Hedin had to return for lack of drinking water. After a year's preparation, Sven Hedin made a special trip to this site on March 3, 2008, and conducted a week-long excavation. After sorting out and analyzing, He Ding named this relic Loulan according to the word Loulan in the unearthed documents. This great discovery shocked the world and won great honor for Sven Hedin.

Later, Stein in Britain and Orange Ruichao in Japan found the Loulan site along the road map of Heding. Their excavation work is more thorough and meticulous, but it is also destructive and predatory. These works have become an important geographical basis for Loulan's future exploration.

Although it is difficult to recognize Loulan City from the landforms of Gobi and Ya Dan, scientists have found from a large number of data and investigations that Loulan City, as an important town on the Silk Road, was abandoned for 1500 years and was once brilliant. According to experts' analysis, Loulan remains have a history of 1800 years. After being looted by the wind and sand, only the broken Populus euphratica wooden frame and several reed walls are left. Judging from the size and building materials of the house, the housing conditions of ordinary people were relatively simple at that time, but a large number of exquisite wooden products and ancient coins left in the ruins reminded people that there were also many wealthy families in Loulan City. Experts believe that there has been a polarization between the rich and the poor in Loulan City. At the same time, these wooden products showed us the exquisite craftsmanship of carpentry at that time and the prosperity of Loulan economy. Experts found that there are dozens of houses like this, which are concentrated in the west of the city to form residential areas, while the east of the city has administrative and military areas. The city has complete functions, clear layout and obvious awareness of urban planning and development.