Yan'an, judging by the geological structure, is a component of Ordos platform of North China platform. Ordos platform, also known as Shaanxi tectonic basin, is bounded by Lvliang Mountain Range in the east, Weibei North Mountain Range in the south (also called Huanglong Mountain Range), Helan Mountains in the west and Yinshan Mountains in the north.
Ordos platform was once the domain of the sea for a long time before the Paleozoic Ordovician period, 500 million years ago. Since the late Paleozoic Ordovician, 460 million years ago, the Ordos platform has begun to uplift into land. Later, after billions of years of crustal movement, the eastern edge of the platform gradually sank during the Paleozoic Carboniferous period about 300 million years ago, causing the seawater to invade again. The coastline at that time was on the eastern edge zone of Yan'an area, that is, the areas of Yanchuan, Yanchang and Yichuan.
The Hercynian movement, which took place in the late Paleozoic Permian Period, 200 million years ago, caused the uplift of Shanxi platform, Liupanshan area and Qinling Mountains around the Ordos platform, making the Ordos platform become an interior basin. During the Mesozoic Triassic period, the northern Shaanxi basin, with the oscillatory movement of the crust, became an interior lake area. The scene of lake swinging continued into the Mesozoic Lower Cretaceous period, 110 million years ago. The platform was lifted due to the Sichuan movement, thus ending the subsidence of interior basins in the area. The fossil of Baleiichthys Antingensis Liu 170 million years ago, found in Tuoerxiang Village, Fengjiatun Township, Zichang County, is a witness of this geological period.
During the Cenozoic Tertiary period, Ordos platform was a subtropical grassland area with hot and humid climate, abundant rainfall and rich vegetation. In this vast grassland, herbivores such as hipparion and gazella gaudryi flourished.
At the end of Pliocene, the Himalayan movement occurred, which affected the area and made the Ordos platform uplift to form a plateau. Fault depression or uplift also occurred around the plateau, which basically laid the foundation for the modern geomorphology of the Ordos platform.
By the Pleistocene period, two or three million years ago, the Wucheng loess, Lishi loess and Malan loess were successively piled up on the Ordos platform. And the Loess Plateau of northern Shaanxi Province was basically formed. The formation of the Loess Plateau is also the dawn of human history.
In 1975, when the Yaomenhe Reservoir was built in Huanglong County, fossils of human skulls were found when taking soil on the south slope of the Xu Cemetery Hill on the north side of the dam land. At the same time, the fossil of Pseudaxis corner was also excavated. The frontal and parietal bones of the fossils of human skulls unearthed have been preserved. Those bones, after identified by the Institute of vertebrate paleontology and Paleoanthropology of the Chinese Academy of Sciences in 1983, were recognized as a transitional type of late Homo sapiens, about 30,000 to 50,000 years from now, and they were named "Huanglong Man".
Huanglong Man came later than Maba Man and Dingcun Man, while they came earlier than Hetao Man, Upper Cave Man and Liujiang Man. It has fully proved that Yan'an is also one of the cradles of human childhood.
In the fall of 1987, microlith including chopper, scraper, steinkern, bunt, pointed tools, etc. were successively found in Longgang Temple Terrace, Luanjiaping Township, Zichang County, Zhaiguan Mountain, Anding Township, Yuju Township and Jiajiaping Township, Yanchuan County, and Xiannangou, Yanhewan Township, Ansai County, etc. This discovery filled a gap in Yan'an history. It shows that Yan'an, after the Paleolithic Age and before the Neolithic Age, was once a place where descendants of the "Huanglong Men" flourished. They were fearless of danger and difficulties. They lived by collecting and hunting.
After the human society entered the Neolithic Age, with the superior geographical environment, Yan'an provided our ancestors with an ideal place to live. The Banpo, Miaodigou and Maquanyao types of Yangshao culture scattered in various counties and cities have shown us an all-time high of prosperity of the matriarchal commune 5,000 years ago. At that time, with a warm climate and dense subtropical plants distributed on the land of Yan'an, tapirs, water muntjac, wild raccoon dog and bamboo rat infested in groups. With abundant water resources and good vegetation, ancestors lived by fishing and hunting. And they also engaged in agriculture, thus realizing the change from gathering industry to planting industry. Millet, i.e. unhusked rice, was the main crop at that time. Even today, for Yan'an people, millet is still one of the main crops. After thousands of years of vicissitudes, the sharp-bottomed bottle, the round-bottomed bowl, stone axe, the stone adze, the stone sickle, the stone net pendant, etc. represent the prosperity in the old days.
About 5,000 years ago, the matriarchal commune gradually disintegrated and became a patrilineal commune. Longshan, as a representative of ancient cultural relics in this period, has been found in many places. The Qijia cultural relic of the same period was also found in Wuqi County. People at that time began to raise cattle, hunt units and weave textiles. The technology of housing construction was improved rapidly. People used natural stones containing rich calcium carbonate as raw materials. They crushed it for water transfer, and then applied it to paint floors and walls, which is often called "living surface". Many pottery and stone implements were found, including stone spinning wheels, pottery spinning wheels, etc., indicating that the social and economic scale at that time was already considerable. The descendants of "Huanglong Man" have crossed the threshold of transition from barbarism to civilization and pushed forward the society.
Besides archaeological materials, myths and legends are also conducive to understand the history of Yan'an in ancient times.
Sun Yat-sen, the great revolutionary pioneer, after the victory of the Revolution of 1911, wrote a magnificent poem: Since the establishment of Chinese nation for 5,000 years, the Yellow Emperor Xuanyuan, the first human ancestor in the wonderful land of China, has been well-known. He created the compass and thus quelled the Chi You rebellion. Of all the civilizations in the world, only our Chinese ancestors are the most commendable.
According to historical records, the Yellow Emperor was the son of Shaodian, a Monarch in Youxiong, he was named "Xuanyuan" and surnamed "Youxiong". Because he was born beside Jishui, his surname is "Ji". The Yellow Emperor was born in Shen Nung era. At that time, Shen Nung was aging, the dukes attacked each other and oppressed the common people. Among them, Chi You, the leader of the Oriental Jiuli Tribe, was the most fierce and brutal, but Shen Nung was unable to mount a military expedition. The Yellow Emperor was the commander of the army. He fought against Chi You in Zhuolu. In this war, it is said that the Marquis of Wind and Master of Rain invited by Chi You (mythological warrior engaged in fighting with the Yellow Emperor) made the wind blow and rain fall, and he spread dense fog out. The Yellow Emperor invited the female Drought God to help him. He also made a southward pointing cart to orientate himself in the dense fog. In addition, he ordered to blow horns sound like a dragon to scare away the demons and capture Chi You. The Yellow Emperor also merged the clan leader of the tribe named Jiang, the Yan Emperor. Since then, the Yellow Emperor was elected as the leader of the union of tribes by ministries to replace Shen Nung.
In the ancient legends, people attributed many inventions to the period of the Yellow Emperor. For example, jade (solid rock) was used as a weapon, vessels, vehicles and arrows were made, colored clothes were dyed, and pots and mirrors were invented. All of these were regarded as the achievements of the Yellow Emperor. As for Cang Jie's word-formation, Ling Lun's production of musical instruments, Da Nao's creation and production of heavenly stems and earthly branches, Qi Bo's writing of medical books, Chang Yi's occupation of the moon, Xi He's occupation of the sun, and Gui Yuqu's fortune-telling, Li Shou's counting, Rong Cheng's creation of calendar, and Hai's cattle riding, etc., they were all invented during the period of the Yellow Emperor. It is said that Lei Zu, the Imperial Concubine of the Yellow Emperor, personally raised silkworms and used them in silk drawing and brocade weaving, thus establishing a milestone in the weaving history.
As the Yellow Emperor unified the tribes in the Central Plains, he was honored as the first ancestor in Tang Yao, Yu Shun and the Xia, Shang and Zhou dynasties. Later, all nationalities in China considered themselves to be descendants of the Yellow Emperor, and they called themselves "later generations of the Yellow Emperor" or "descendants of the Yellow Emperor".
Legend has that the Yellow Emperor once collected copper from Shoushan to cast a "Ding" on Jingshan. On the day when "Ding" was built, there was a dragon flying from the sky hanging down a beard to meet the Yellow Emperor. The Yellow Emperor rode the dragon, and more than 70 ministers and personnel from the imperial harem followed.
The ministers of the Yellow Emperor, Zuo Che and others, also wanted to ascend to heaven. They grabbed the skirt and boots of the Yellow Emperor, but they were powerless, and only pulled down a boot and a skirt. Then Zuo Che buried the Yellow Emperor's boot and skirt at the top of Qiaoshan. However, according to Shih Chi · Annals of the Five Emperors: "The Yellow Emperor is dead and buried in Qiaoshan." This is the Huangdi Mausoleum in Qiaoshan, Huangling County. In the Han Dynasty, the Temple of Yellow Emperor was built at the foot of Qiaoshan. Since the Qin and Han Dynasties, Chinese dynasties and governments have assigned officials to offer sacrifices to ancestors and pay homage at their mausoleums on Tomb-Sweeping Day and national ceremonies. On Apr. 5, 1937, Mao Zedong, Chairman of the Soviet government, and Zhu De, Commander-in-chief of the People's Anti-Japanese Red Army, assigned a representative, Lin Boqu, to the Huangdi Mausoleum to offer sacrifices to the Yellow Emperor. Chairman Mao Zedong also wrote the funeral oration in person: "The first great ancestor created our Chinese nation. His descendants breed in an endless succession, and the joss sticks and candles last forever. There are high mountains and surging and vast rivers. His wisdom shines on the remote and deserted frontier. The great cause of the Chinese nation established has stood in the east of the world......"
The Yellow Emperor is the first ancestor of the Chinese nation; and the Huangdi Mausoleum is a sacred place for the Chinese nation and a symbol of unity for the descendants of the Yellow Emperor at home and abroad.
Yu was born in the Yao and Shun era in the later period of the clan system. Legend has it that he was the great-great-grandson of the Yellow Emperor. According to legend, China, in the Yao era, suffered a terrible flood disaster. The rivers overflowed and people suffered greatly. Yao sent Yu's father to control water, but after nine years, he still failed. After the death of Yao, Shun was elected as the leader of the union of tribes, and sent Yu to continue to control the flood disaster. Yu accepted the lesson of his father Shun's failure in water control. He built dikes, blocked water and dredged rivers. At last, Yu overcame the flood.
Yu, the Great successfully controlled water at Hukou Waterfall for the first time. According to Mister Lv's Spring and Autumn Annals · Chapter Ai Lei: "In ancient times, the Longmen Mountains had not yet been excavated, and the Lvliang Mountains had not yet been opened up. The Yellow River had overflowed from the Mengmen Mountain, and the flood was rampant. No matter the hills, fertile land, plains and high mountains were all submerged, people called it "Hongshui". Yu then dredged up and guided the river, and built a dike at Penglize, making the floods in the east subside, saving more than 1,800 countries. This is Yu's achievement! No one can match Yu's hard work for the people". According to Commentary on the Waterways Classic: "Mengmen is the entrance to Longmen. It is really a huge mountain pass in the river, also known as "Mengmenjin". In the legends, Longmen was carved by Yu the Great. The river channel was very wide because of the impact of water. The water was sandwiched by a long section of mountains, with cliffs on both sides. The boulders on high seemed to fall off the cliffs. The water flows in Longmen meet and impact, and white moisture floated in the air like clouds." There is a village called "Yuju" in Wenanyichuan, Yanchuan County. It is said that it was the place where Yu lived when he went to Yongzhou for field investigation and survey, so it was named "Yu". When Yu lived in Yijin Village, Yichuan, he married a woman surnamed Zhou. People here later built a King of Yu Temple. Because Yu is a "Guye" (refers to paternal grandaunt's husband) in this village, so the temple was named "Gufu Temple"
It is said that Yu spent 13 years controlling the flood. During this period, he passed by his home three times but didn't go in. Even when his wife gave birth, he didn't go back home. With tools and compasses, he took part in work. He was so tired that he became very thin. After the flood retreated, Yu led people in productive labor. He asked Yi to distribute rice seeds to people for sowing, and asked Hou Ji to teach people to plant crops. The people survived the famine after the flood.
Yu was highly respected by people. According to the Book of Songs · Xiaoya · Xin Nan Shan: "Zhongnanshan Mountain stretches for a long time, and this is the site created by Yu the Great." Huoya · Han Yi: "Liangshan Mountain is towering and tall, and Yu the Great once conducted governance here." Daya · Wenwang Yousheng: "The abundant water flows eastward, which is the achievement of Yu the Great." Shangsong · Chang Fa: "Thinking of the vast flood in the primordial times, Yu the Great controlled water in the world". People focus on Yu alone for the excellent character of "serving the people and the nation". Yu the Great is the national soul of the Chinese nation. Hukou Waterfall and Mengmen Mountain, the holy relics left by Yu the Great, vein the blood of nation, beat the pulse of nation and gestate the soul of nation. Hukou Waterfall is a great symbol of our nation's ceaseless self-improvement and stubborn independence in the world nationalities.