Around 3000 BC, Sumerians who migrated from outside to the arid and rainless areas in southern Iraq used river water to irrigate farmland and invented the world's earliest characters-cuneiform characters, thus creating a number of the earliest city-states and splendid Sumerian civilization. Under the influence of Sumerians, the local Akkadians who spoke Sem in the two river basins joined the stage of civilization history, and successively established two empires, Akkadians and the Third Ur Dynasty, standing side by side with Sumerians. Subsequently, although Sumerian civilization continued to spread to the surrounding areas, and Assyria in the northern part of the two river basins was included in the civilization circle of the two river basins, it developed into a famous Babylonian-Assyrian cuneiform civilization (hence the name Assyrian, a modern humanities discipline), but the population of Sumerian seemed to be decreasing. In 2004 BC, the Ur III dynasty of Sumerian royal family was replaced by two dynasties, Ishin and Larsa, which were established by the emerging Samian-speaking Amorites. From this period, some Sumerian city states, such as Lahashi, Marvin and Shurupak, began to decline. Many cities began to decline and finally became desolate ruins. Babylonian dynasty, a branch of Amorites who recently moved into the two river basins, was a nomadic tribe, founded in Babylon near Baghdad, and defeated the Ishin and Larsa dynasties in the southern Sumerian region, thus ruling the whole country. With the gradual abandonment of a large number of cities in the south, Sumerians disappeared completely among Babylonians. A thousand years later, although the Babylonians and Assyrians pushed the civilization of the two rivers to the peak, the emerging Persians on the Iranian plateau conquered the two rivers and adopted cuneiform culture. In 33 1 BC, Alexander, the conqueror representing Greek civilization, conquered the whole West Asia, and the new Hellenistic civilization began to replace the old cuneiform and hieroglyphic civilizations in West Asia and North Africa. Soon, like many Sumerian cities a thousand years ago, all the ancient cities of Babylon and Assyria were abandoned one after another, and the civilizations in the two river basins were soon completely lost. The reasons for the extinction of civilization in the two river basins, which lasted for three thousand years, are complicated. On the one hand, the conquest and substitution of external emerging civilizations such as Greece and Islamic civilization are important reasons; On the other hand, the over-development of agriculture has worsened the ecological environment with congenital deficiency, which is also a major internal cause. 1982, in the book Ancient Saline Land and Irrigated Agriculture, Jacobson, a famous American Assyrian scientist, discussed the relationship between irrigated agriculture and land salinization in southern Sumerian region of two river basins, and pointed out that this was an important reason why Sumerians withdrew from the historical stage prematurely.
The land in southern Iraq (Sumer) is fertile alluvial clay, which is suitable for growing grain. But the climate is dry and there is little rain, so we can only rely on artificial irrigation for agriculture and date orchard production. However, both local land and river water contain exchangeable sodium ions and salts. Usually, sodium ions and salts are carried into the groundwater layer by water. As long as the groundwater level keeps a certain normal distance from the surface, groundwater containing sodium salt can't harm farmland. The ancient Sumerians only knew about watering, but they didn't know that the salt accumulated in the land had to be filtered and channeled, and it was completely excreted with enough water. As a result, with a large amount of irrigation, the salinity of the local groundwater layer increased year by year. When excessive water seeps into the groundwater layer, the salty groundwater level will rise and invade the surface layer under the capillary action of the land, thus salinizing the land. The French archaeological team found a large number of agricultural and economic clay tablets from the Sumerian city-state hegemony period (about 2300 BC) to the end of the third Ur dynasty (2004 BC) from the Gilsu site in Sumerian city. These 400-year-old documents tell us that from the beginning, the problem of land salinization accompanied by ancient irrigated agriculture has been puzzling the farmers and nobles in Sumer. It is possible that this vicious circle eventually led to the permanent abandonment of a large number of Sumerian cities represented by Gilsu in the late Babylon (about 1700 BC). The deterioration of the ecological environment may gradually reduce the population of Sumerians, the creators of civilization in the two river basins, and some cities will be completely abandoned. Therefore, the center of civilization moved from Sumer in the south to Babylon in the north, which led to the premature demise of Sumer's race, language and civilization.
The salinization of farmland in Sumer area is also reflected in the local crop varieties and yield per unit area. It is found that the container (74) containing wheat is similar to the containers (43, 39) containing barley in the Uluruk cultural site in the early civilization. [8] When the land began to salinize, the salt-tolerant wheat crops began to decrease year by year. In 2400 BC, wheat accounted for 16% and the rest was barley. About a hundred years later, during the Akkadian dynasty, wheat fell to 3% of the planting area. According to a document of the Third Ur Dynasty, wheat only accounted for 1.86% of a piece of land in Gilsu at this time. Later, Sumerians could hardly grow salt-tolerant wheat. Although barley is salt-tolerant, salinization of land will reduce its yield. According to the unearthed documents in Gilsu, the barley yield per hectare was 2537 liters in about 2400 BC, and decreased to 1460 liters in 2 100 BC. About 1600 BC, it is very likely that the land in Jiersu City was seriously salinized, which led to the complete abandonment at this time. At this time, the barley yield in a certain area of Larsa, a neighboring city, is only 897 liters per hectare.
Until modern times, farmers in southern Iraq have been struggling with land salinization. Their long-term practice shows that fallowing and planting grass in each season can slow down the rise of groundwater level. When the local sewage finally reached the surface and the farmland was completely salinized due to years of irrigation, they completely gave up these inferior farmland. After decades or even hundreds of years of drying and evaporation, when the groundwater level drops to a considerable depth, future generations of farmers will return to these restored lands again.
-Clay from Sumerian civilization (Wu Yuhong)