In 400 A.D., the high monk Fa Xian traveled west to learn scriptures, passing through this place, he said in the "Buddha's Country Record" that this place has been "no birds on the top, no beasts below, all over the eyes, only the dead dry bones as the mark ear". After nearly 500 years of glory, Loulan - this important town on the Silk Road gradually lost its population and disappeared silently on the stage of history.

How was Loulan destroyed?

According to the record of "Notes on the Book of Water", after the Eastern Han Dynasty, due to the diversion of the Zhubin River in the middle reaches of the Tarim River at that time, there was a serious shortage of water in Loulan. Dunhuang Soler led 1,000 soldiers to Loulan, and summoned 3,000 soldiers from Shanshan, Yanqi and Qiuci to cross the riverside day and night to divert water into Loulan, alleviating the dilemma of water shortage in Loulan. But after that, despite the best efforts and attempts made by the people of Loulan to dredge the river, the ancient city of Loulan was eventually abandoned due to water cuts.

In fact, the main cause of Loulan's demise was an existential crisis caused by a lack of water.

How could Lop Nur, the largest water source in Loulan, move? Scientists believe that in addition to the factors of crustal activity, the biggest reason is the accumulation of large amounts of sediment in the riverbed. The sediment in the Tarim River and the Peacock River converged at the mouth of Lop Nur, and as the days went by, the sediment accumulated more and more, silting up the river, and the Tarim River and the Peacock River found a new way to flow to the low-lying places, forming a new lake. In the hot climate, the old lake gradually evaporated and became a desert, and water is the source of life for all things in Loulan City. The northward movement of Lop Nur Lake made Loulan City thirsty for water, the trees died, and the citizens abandoned the city, leaving a dead city, and in the raging desert storm, Loulan was finally annihilated by the sand dunes.

The disappearance of Loulan is also related to the destruction of the ecological balance of nature. Loulan is located on the main route of the Silk Road, and the Han, Xiongnu and other nomadic countries often provoke wars in the territory of Loulan; For the sake of the country's interests, excessive reclamation has caused serious damage to water conservancy facilities and good vegetation: "After the third century AD, the riverbed of the lower reaches of the Tarim River, which flows into Lop Nur, was silted up by wind and sand, and it was diverted to the south in the southeast of present-day Yuli, causing Loulan to "be surrounded by people and cut off from people", "the country has been empty for a long time, and the city is deserted." ”

Lop Nur was once the largest lake in the arid region of northwest China, with a lake surface of 12,000 square kilometers, and at the beginning of the last century it still reached 500 square kilometers, when the Loulan people built more than 100,000 square meters of Loulan ancient city near Lop Nur, but by the 20th century, it eventually dried up. What caused Lop Nur, which was once rich in water and fish, to become a vast desert? What was the reason why the ancient city of Loulan, the key point of the Silk Road, became an inaccessible desert Gobi? This has always been a scientific mystery.

About 10,000 years ago, the earth's environment underwent unprecedented changes, that is, from the dry and cold environment of the last glacial period to the humid environment of the post-glacial period, and human culture also entered the Neolithic period from the Paleolithic Age. After 10,000 years, the geological environment has undergone three major stage changes, about 10,000 to 8,000 years ago for the warming period, about 8,000 to 3,000 years ago for the high temperature period (climate suitable period), and 3,000 years ago for the cooling period. These three environmental patterns have been confirmed by the study of geology, biology, chemistry and physics, but there are slight differences in the timing of the three phases due to different methods, locations or research objects. This change in the environment and climate has shaped the scope and mode of human activities.

Taking Loulan as an example, the Neolithic Age human beings set foot here, the Bronze Age was prosperous here, and it was during the high temperature period, the Lop Nur Lake was vast and the environment was suitable. However, after entering the cooling zone, the water and soil environment deteriorated, the river water decreased, the lake shrank, and the desert expanded. Drought intensified around 2000 years ago, which was manifested in the occurrence of ice ingress in vast areas of northern China, the accumulation of loess, the extinction of lakes and marshes, and the retreat of the sea.

The ancient city of Loulan fell from about the second to the fourth century BC (from the Han Dynasty in the Central Plains to the Northern Wei Dynasty), which was a period of increasing drought. In fact, in this process of drought, not only the ancient city of Loulan disappeared, but also due to the expansion of the desert, the extinction of Niya, Karadun, Milan City, Niyang City, Khan City, Tongwan City and so on occurred successively.

The demise of the ancient city of Loulan occurred in the context of the drought of northern China and even the world's climate, it is not an isolated space, but because Loulan is located in the arid interior, the changes in the human and natural environment here are more significant.

The impact of human activities on the drying up of Lop Nur can be said to be increasing. Water and trees are key to the survival of an oasis in the wilderness. The ancient city of Loulan was built in the lower reaches of the Peacock River Delta, where the water system was developed, and there were once flourishing poplar trees for its construction. At that time, the Loulan people built more than 100,000 square meters of the ancient city of Loulan near Lop Nur, and 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, changes in water systems and the destruction of wars have further deteriorated the already fragile ecological environment. The densely planted "male root stump" on the cemetery of Xiaohe No. 5 shows that the Loulan people felt the survival crisis of the tribe at that time, so they had to pray for fertility worship to bless their children and grandchildren. But they cut down already scarce trees in large numbers, adding to the already deteriorating environment.

The eventual drying up of Lop Nur is related to the overexploitation of the upper Tarim River after liberation in the 20th century. After the government diverted a large amount of water from the upper reaches of the Tarim River, the water of the Tarim River could not make ends meet, and the downstream flow was cut off. This can be confirmed by the fact that the Yellow River has been cut off. Lop Nur also began to shrink rapidly due to the lack of water supply, and finally died out.

In order to avoid the irreparable permanent survival disaster caused by the ecological disaster in Gaochang and the northwest region, the population density of the grassland and the ecologically fragile foothill alluvial fan area in the northwest was forcibly controlled within a reasonable range, and the surplus population was relocated to various cities in Gaochang and Gansu Road, preparing to reserve labor and markets for the imminent start of industrialization.

After going around all the ancient ruins of Buddhism in the Western Regions, Zhang Bo handed in a detailed plan for the rescue of ancient civilizations, including the rescue excavation of cultural relics and information carriers of each site, the compilation of recoverable dead characters, the investigation and research of the remnants of various ancient civilizations, and the ecological restoration and civilization reconstruction plan.

This cash-burning scheme has little hope of recovering its costs within a decade. It would have been impossible for the Crossing Congregation to support. However, Gao Chang, who urgently needed to make good friends with the Great Song Dynasty, took over the hat of the unjust investment and contracted more than half of the expenditure, mainly responsible for the manpower and material resources invested in excavation and ecological restoration.

The purpose of this is also very simple, the Gaochang monarch Vijab Jin, who was baptized by Zhang Bo's consultation, sees the future crisis of his race, and hopes to change the environment and situation in the surrounding area.

This expenditure of nearly 3 million guan made Vigab's jin painful, but it still made the traversal who controlled public opinion give Vigab's jin a high evaluation, and also won a lot of folk praise and affirmation for himself. In order to obtain more state-owned land, Gaochang had to start from the less productive desert and the saline-alkali swamps of the Tarim River.

The use of environmental technology can effectively improve the productivity of the region and help the whole of Gaochang to enter the fast lane of sustainable development. The money spent for the benefit of the country and the people is always not obvious, and Zhang Bo has become the most proficient of the five brothers who can spend money and solicit sponsorship, which is almost the exact opposite of the introverted image of silence and thrift during his studies.

The only destabilizing factor in the northwest was the divided Qarakhanid kingdom, and the Eastern Qarakhanid's eye on the top could not be offset by a small amount of trade that could be said to make the Tibetan leader Lun Rozan disdain. When the cost of coveting Gaochang's growing wealth is less than the risk of war, it is the moment when war begins.

In order to get rid of the Qarakhanid who converted to Islam, Gao Chang, who believed in Buddhism, was simply heartbroken. Although the Great Song Dynasty opened up almost all the import and export of goods, the opening of the arms quota trade was never approved by the Great Song court. The reason is not the sanity or inefficiency of the imperial court. It's about passing through the obstacles of the multitude.

Wang Xinyu knew that once the arms exports were opened, the wealthy Gaochang might destroy the Qarakhanid, which was not in line with the strategic planning and future layout of the Crossing People. His own smuggling team and the northwest forces will be weakened by the strength of Gaochang. The core of the entire Eurasian region is the impoverished and backward Qarakhanid region, which is of great strategic value, and just as the United States will occupy Afghanistan in the future era of globalization, the people cannot agree that anyone other than themselves will control the core of the world island.

The second half of Zhang Bo's plan consisted of military and political aspects in addition to the cultural and religious aspects of buying people's hearts, establishing strongholds, expanding influence, and increasing authority.

The old and young, who originally had high hopes, only established meritorious deeds in the cultural and religious fields, and once again appreciated Zhang Bo's scheming and pattern. The content of the plan, which may not even be accepted smoothly by the crossers, is simply a small and broad stroke of genius, and can almost be used as a model for future expansion into West Asia and the Near East. Detailed strategies were drawn up for all the central and western Asian countries as far as Segani and as far as Eastern Rome.

This is simply a Han version of the Mongol Western Expedition with economic colonization as the main axis, military deterrence as the forerunner, ethnic and religious cultural integration as the auxiliary, and political inducement as the means. Under the banner of saving all ancient civilizations, they are doing what imperialism loves to do.

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