The Great Wall began in the Warring States period, and Qin, Zhao and Yan built it in the north. The Warring States period is a period of transition from slave society to feudal society in the middle and lower reaches of the Yellow River and Yangtze River in China. With the strengthening of political and economic relations among countries, the exchange and integration between Zhu Xia culture and Qin Chu Wuyue culture is increasingly strengthened. When the seven countries, Wei, Zhao, Han, Chu, Qi, Qin and Yan, which were undergoing feudal reforms at that time, became strong, they waged a war of annexation and sought to unify the middle and lower reaches of the Yellow River and the Yangtze River by force. At this time, the ethnic minorities in the grasslands of northern Shaanxi, northern Shanxi, northern Hebei and Inner Mongolia also became powerful and plundered the northern borders of Qin, Zhao and Yan. The northern part of Qin is Yiqu, and the northern part is Xiongnu. There are Hulin and Loufan in the northwest of Zhao, and Huan and Xiongnu in the north. Donghu, the northern boundary of Yan State. These northern minority regimes, except Yiqu engaged in agriculture, all made a living by nomadic and hunting. Yiqu is a powerful country on the Loess Plateau in northwest China. From the Spring and Autumn Period to the Warring States Period, Yiqu competed with Qin for more than one hundred years. Xiongnu, Donghu and other nomadic peoples have high military quality and strong combat capability. According to Records of the Historian Biography of Huns, Huns lived by nomadic and hunting, and horses, cattle and sheep were the most livestock, followed by camels, donkeys and mules. They "migrate by water plants and don't have to live in the city to farm." However, there are also important points. "Men learn to ride horses and shoot at an early age. "Children can ride sheep and shoot birds and mice with bows; If it is not too long, it will shoot foxes and rabbits; Use it to make food. Therefore, once you are an adult, you will become a "rider". "During the Warring States period, the Huns had entered the slave society and had state power institutions. The king is called Khan. He has left and right sages, left and right kings, left and right generals, left and right commanders, left and right leaders and left and right leaders. Except for the right and left ministers, all the other ministers are hereditary. Donghu, Hu Lin, Huaneng and Loufan are basically the same as Xiongnu. Since the mid-Warring States period, they have been plundering the northern regions of Qin, Zhao and Yan. Because they are good at riding and shooting, good at fighting, taking sudden attacks, coming and going, elusive, showing strong combat effectiveness. In the mid-Warring States period, the combat troops of Qin, Zhao and Yan were mainly infantry and chariots. They wore big sleeves and took off their coats. They moved slowly for 30-50 miles every day. Naturally, they couldn't stop the Huns and Donghu people from attacking and plundering. This not only seriously threatened the safety of people's lives and property in the northern areas of the three countries, but also seriously damaged their production and greatly affected the cause of reunification of the three countries. In response to this passive situation, the three countries successively carried out military reforms and built the Great Wall in the north. Since Shang Yang, Qin began to reform and promote Qiang Bing, a rich country. The army gradually transformed into infantry and cavalry, and was rewarded and promoted for its military achievements, so the combat effectiveness of the army increased and it was invincible. King Huiwen defeated Wei in six years (the first 332 years) and ten years, and captured Weixi County (now Luohe Valley in Shaanxi Province) and Shangjun County (now northeast Shaanxi Province). In order to prevent the Huns from plundering the south, Zhao Haoqi ordered the Great Wall to be built on the northern border of Longxi, Beidi and Shanjun, and sent troops to station it. In the 19th year of King Wuling of Zhao (307 BC), he began to reform the military system and was carrying out riding and shooting. Since then, the troops have become more powerful. In twenty years, King Wuling went west to the lakeside and arrived in Yuzhong. King Hu Lin surrendered his horse before returning home. In the twenty-six years (the first 300 years), Zhongshan was broken, and the prosperous place reached Yan and Dai in the north (now northwest Shanxi), and then extended to Yunzhong and Jiuyuan in the northwest (now the area from Helinger County to Wujiahe in Inner Mongolia). Therefore, the Great Wall was ordered to be built, which merged with Yinshan Mountain (now Daqingshan Mountain and Wulate Mountain in Inner Mongolia) and extended westward to reach Dahe River (now Wujiahe River in Inner Mongolia), and Dai Jun County, Yanmen County and Yunzhong County were set up at the same time to prevent Huns from plundering south. In order to specialize in the northwest, the next year, he gave way to his son He, who was appointed as the main father. In the second year of King Huiwen (297 BC), his father went out of Xihe (the Yellow River between Shanxi and Inner Mongolia), and the ruined building angered the king and sent troops. Yan State is the weakest country among the Seven Heroes in the Warring States Period, bordering Qiangqi and the newly established Zhao State in the south and forcing Donghu in the north. It was not until he ascended the throne (the first 3 1 1) that Yan became strong, recruited talents and carried out reforms. At that time, Donghu was powerful and often plundered the northern part of Yan State. In order to keep the peace in the north, the Yan army was forced to make peace with King Donghu and took the general as a hostage. Zhao Shi was born in East Lake. He is clever and brave, and King Donghu trusts him very much. Therefore, he can move freely, and he can understand the dangers of mountains and rivers in the south of East Lake, the protection situation and the laws of military activities. After returning home, he led an army to attack Donghu, which was broken, but Donghu was thousands of miles away. And "crossing Liaodong to attack North Korea" was extended to Tanshui (now Qingchuan River in North Korea). So, "Yan also built the Great Wall to make Yang (now kangbao county, Hebei Province, Taibus Banner, Inner Mongolia) go to Xiangping; Put on the valley, Yuyang, Youbeiping, western Liaoning and Liaodong counties to refuse Hu. "To sum up, during the Warring States Period, the reason why Qin, Zhao and Yan built the Great Wall in the north was to defend against Xiongnu and Donghu from the south. The Great Wall is developed from cities and castles. As a military defense project, cities and fortresses began as early as the end of the primitive commune. Because it can play an effective defensive role, it has been generally developed since it entered the class society. The Great Wall first appeared in the Spring and Autumn Period, such as Fangcheng of Chu State (in the present Nanyang area of Henan Province). During the Warring States Period, there were the Great Wall of Weixi County, the Great Wall of Zhangzhao Water, the Great Wall of West Zhongshan, the Great Wall of Yanyi Water and the Great Wall of Taishan Mountain. These Great Walls once played a great role in the war. The swift cavalry of nomadic people in the north is unpredictable. No matter whether it is infantry or cavalry, all countries can stop their attack and plunder. Only by building the Great Wall and garrison defense can they be prevented from plundering the south. Only by building the Great Wall in the north can we deploy the main forces for annexation and defense wars between countries and complete the great cause of reunification. Meng Jiangnv cried at the Great Wall. According to legend, in the Qin Dynasty, there was a kind and beautiful woman named Meng Jiangnv. One day, when she was doing housework in the yard, she suddenly found a man hiding under the grape trellis, which startled her. She was about to shout at Mengjiang Temple when the man waved his hand again and again and begged, "Don't shout, don't shout, help me!" "My name is Fan Xiliang, and I am here to escape." It turned out that Qin Shihuang arrested people everywhere for labor in order to build the Great Wall. I don't know how many people starved to death and how many people were exhausted! Meng Jiangnv saved Fan Xiliang. When she saw that he was smart and beautiful, she fell in love with him, and Fan Xiliang also fell in love with Meng Jiangnv. They are soul mates, and with the consent of their parents, they are going to get married. On the wedding day, the Meng family was decorated with lanterns and colorful decorations, and the guests were beaming. Seeing that it was getting dark, the people who drank the wedding banquet gradually dispersed. When the bride and groom were about to enter the bridal chamber, they only heard a chicken flying and a dog barking. Then a group of evil officers and soldiers broke in. It's hard to say that they chained Fan Xiliang and took him to the Great Wall to work. The happy event went up in smoke, and Meng Jiangnv was sad and angry, missing her husband day and night. She thought that instead of sitting at home in a hurry, I would go to the Great Wall to find him myself. Yes! Do it! Meng Jiangnu immediately packed her bags and set off. Along the way, I don't know how much wind, frost, rain and snow I have experienced and how many dangerous mountains and rivers I have trekked. Meng Jiangnv never shouted a bitter word or shed a tear. Finally, with tenacious perseverance and deep love for her husband, she reached the Great Wall. At this time, the Great Wall is already a long wall composed of construction sites. Meng Jiangnv searched from construction site to construction site, but never met her husband. Finally, she got up the courage to ask a group of migrant workers who were about to go to work: "Do you have Fan Xiliang here?" Migrant workers said: "There is such a person, a new person." Hearing this, Meng Jiangnv was extremely happy! She quickly asked again, "Where is he?" The migrant workers said, "They are dead, and the bodies have been filled at the foot of the city!" " "Suddenly heard the bad news, like a bolt from the blue. Meng Jiangnv only felt black at the moment and burst into tears. I cried for three days and nights, and I cried so dark that even the sky was moved. It's getting dark and the wind is getting stronger and stronger. There was a crash, and a section of the Great Wall collapsed, revealing Fan Xiliang's body. Meng Jiangnv's tears dripped on his bloody face. She finally met her beloved husband, but he never saw her again because he had been killed by the cruel Qin Shihuang.