Where does the corn come from?

Corn planting and population migration of sages I corn, namely corn, can be seen everywhere in Yunnan, especially in mountainous areas. Is this extremely common crop really related to the development of immigrants? I have read a book, Population and Related Issues in the Early Ming Dynasty 1368- 1953. The writer is He Bingdi, a former professor at Columbia University and chairman of the Asia Society of America. He believes that the cultivation of corn and the development of immigrants in the Ming and Qing Dynasties are closely related to them. He pointed out that people should pay attention to the contribution of newly introduced crops such as corn and sweet potato when summing up the great population achievements in Ming and Qing Dynasties. In addition to rice, a large number of baogu are planted at the two foothills of Gaoligong Mountain. Baogu is not the original crop here. The original crops at the two foothills of Gaoligong Mountain were only rice. Geng Deming, an archaeologist in Baoshan, told me that four Neolithic cultural sites were discovered at the eastern foot of Gaoligong Mountain. There was a great leap forward, which proved that the original inhabitants of western Yunnan were some agricultural nationalities, different from the nomadic "Kunming" people. The discovery of wild rice grains in western Yunnan has also proved this point. Nowadays, in addition to rice, a lot of corn, namely corn, is planted in rural areas of western Yunnan, which originated in South America. American Indians began to grow it 7000 years ago. It was there that I first saw corn, and later I learned that corn was grown in North and South America. 1494, he took it back to Spain. With the development of the world navigation industry, the corn elephant has grown wings and flew all over the world, becoming one of the most important food crops. Today, corn is planted in all continents of the world, and it has become the most important feed crop in the world. In the world, although there are also feed crops such as barley and sorghum, compared with corn, the output is only the tip of the iceberg and a drop in the ocean. In the world, corn accounts for more than 65% of coarse grain output except rice and wheat, and it has accounted for 90% of coarse grain output in China. In China, corn cultivation has only a history of more than 400 years, and its spreading time is 15 1658 in the 65th century. Or from Mecca to northwest China, descendants of Central Asia, and then to inland provinces. On the one hand, it is spread by sea, first planted along the coast and then spread to inland provinces. After textual research, He Bingdi believes that corn first entered China, which should be in the border area of Yunnan and Myanmar. Tengchong is in the area he said. Corn plants are tall, need a lot of water, and like high temperature and loose and fertile soil. The east and west sides of Gaoligong Mountain are sunny. The climate is mild, which is just suitable for the growth and planting of corn. It is natural that the corn introduced to China from the Western Regions was first planted in Baoshan and Tengchong. But Baoshan and Tengchong were sparsely populated at that time. At this time, there were frequent wars in that area, and the original army in China provided sufficient labor for defending the southwest territory and entering the frontier in large numbers, and also for planting corn. In ancient Tengchong, However, there are ancient roads and Sao roads throughout the territory, and there are mountains and rivers winding in the north and south. It is not only the main road of traffic, but also the barrier of traffic. When you enter, you can drive straight to the southwest, and when you leave, you can protect yourself with natural barriers. Has always been a battleground for military strategists. From the Western Han Dynasty to the Ming and Qing Dynasties, the imperial courts in the Central Plains did not dare to treat it lightly. They all sent heavy troops and set up county control. As early as the Ming Dynasty, they sent the largest number of troops. Hongwu 2 1 and 29 years rebelled against Silunfa in Luchuan, and Mu Ying led the army to break through. In March of that year, when it was cut again, the four lunfa were completely annihilated; In the sixth year of Ming orthodoxy, Lu Chuan thought that he was the leader of governing the country according to law. In order to safeguard national unity, the imperial court ordered Wang Ji, the minister of war, to lead thousands of soldiers in Beijing camp, Shanghai, Sichuan, Guangdong, Guangxi and other places to initially conquer Sichuan; In the eighth year of orthodoxy, Wang Ji once again led the troops to levy Lu Chuan; Orthodox 13, Wang Ji unified130,000 soldiers, three-levy Lu Chuan; In Wanli 10, Tu Yuefeng set out to attack Wandian (now Changning County, Baoshan City) with 22 inscriptions in Yunnan and Wan Fang. The following year, the guerrilla generals of Tengyue, Liu 19, Deng Zilong (now Baoshan), each with 5,000 men, defeated the Burmese soldiers and recovered their lost territory. These troops came to Yunnan and came to the foot of Gaoligong Mountain, which seems to be purely a military need, but that is only part of their task, and the potential motivation is also to cope with the growing population pressure in the mainland, that is, an immigration development of great migration. According to He Bingdi's research, corn and sweet potato began to be exported to China in the16th century. These crops, combined with the traditional intensive cultivation methods in China, have greatly improved the grain production capacity in China. On the other hand, the steady growth of grain output has created conditions for large-scale population growth. The long-term peaceful and stable social environment, abundant land resources and the imperial court's expenditure on land reclamation all stimulated the population growth. At that time, the population of China "increased from about 65 million in the late 4th century to about10.50 billion in the 28th year of Wanli (1600)". During the period from Kangxi to Qianlong in Qing Dynasty, the population of China exceeded 300 million. He Bingdi pointed out that the great population growth in China during the Ming and Qing Dynasties could not but be attributed to the contribution of newly introduced crops such as corn and sweet potato. It also promoted the development of hilly and mountainous areas in Ming and Qing Dynasties. Many once barren mountain deep pipes were gradually reclaimed by swarming immigrants and turned into new settlements. Large-scale domestic immigrants promoted the expansion of corn planting, and in turn, new crops such as corn became the new driving force for the development of immigrants in the Ming and Qing Dynasties. "Until the beginning of18th century, most hills and mountains in Nanling Mountains were still covered with forests. Agriculture is not very developed. The increasing population pressure in the southeast coastal provinces finally forced the poor farmers in the southeast to reclaim the hills and mountains in the inland provinces of the Yangtze River basin. This process may last until the Taiping Heavenly Kingdom. " Immigrants mainly live on corn and sweet potato. "As a result, these two relatively new crops have become the main means to systematically develop the highlands in the Yangtze River basin." The red topsoil in the hilly areas of Jiangxi and Hunan was covered with vegetation at that time. It was quite fertile when it first became a field of corn and sweet potatoes. By the beginning of the18th century, many mountainous areas in the interior of the Yangtze River valley had been reclaimed, so that immigrants and local Han people invaded the Miao nationality's home-Xiangxi Mountain, and things did not stop there. Except for Jiangxi and Hunan, from16th century to19th century, corn planting promoted the process of reclaiming steep mountains all over the country. Immigrants began to flock to the mountainous areas of northwest Zhejiang in the south of China, the mountainous areas of Yunnan, Guangxi and Guizhou in the south of Anhui, and even the Hanshui River basin in the north. Until the thirty-ninth year of Kangxi (1700), this "vast mountainous area dominated by Qinling Mountains, except for a few towns with historical status or strategic significance that were developed earlier, was still sparsely populated, and most of them were covered by virgin forests". The rapid development of these areas has become a reality. The development of the Yangtze River basin, Yunnan-Guizhou-Sichuan and the hilly areas in northwest China led to "a major revolution in land use in the 18th and early 19th centuries", which increased the total amount of cultivated land. With the development of immigration and corn planting, a large area of forest has been destroyed and disappeared, followed by serious soil erosion. Not only the forests in Hunan, Jiangxi, Shaanxi and other places have been destroyed, but even in remote areas like Yunnan, "in the southernmost three States of Hua Kai, Guangnan and Pu 'er, the virgin forests that were once famous for malaria epidemic were cut down by immigrants from Hunan, Hubei, Sichuan and Guizhou 30 years ago in Daoguang (1850). Even in the westernmost area of Yunnan bordering Myanmar (/kloc-corn was introduced to China in the 6th century), it was still absorbed from the first half of the 9th century.