In recent years, the "prosperous Kangqian era" has been a hot topic, and not only has it been broadcast on television, but even some historians have been preaching it, as if the wisdom of certain rulers could bring prosperity to China. But is that really the case? A careful reading of history shows that there were basically no scientific and technological inventions during this period, there was no cultural prosperity, and the thought was stagnant, industry and commerce were curbed by the government, and the prosperity of commerce and handicrafts in China during the Ming Dynasty had declined greatly. The only development compared to previous generations was a significant increase in population, four times the previous historical peak, resulting in a period of seemingly prosperous society.

The reason for this demographic prosperity is what Qing historians believe was brought about by the wise Manchu rulers. Their first reason was that the Qing Dynasty had expanded its territory. How much population did the Qing Dynasty's expansion bring to China? At its peak, the Qing Dynasty had a territory of 13 million square kilometers, while the Ming Dynasty had 9.2 million square kilometers. Comparing the territory of the Qing Dynasty with the Ming Dynasty, the Qing Dynasty had more Mongolia and northern Xinjiang, but these places are still sparsely populated, and it is difficult to say what additional population will be added to China. Moreover, the Qing Dynasty had a large less territory in the northeast and southwest than the Ming Dynasty. Therefore, in terms of territory, the population of the Qing Dynasty should not be much different from that of the Ming Dynasty.

The second reason cited by Qing historians is how diligent the Qing rulers were, and how much they attached importance to water conservancy and agriculture. Compared with the previous Chinese population, when it was known as the "rule of Hanjing", the "rule of Zhenguan" was only 60 million, and the maximum was only 100 million in the middle of the Song and Ming dynasties. Moreover, throughout previous history, once the Chinese population reached more than 80 million, the contradictions between man and land were very acute, and peasant uprisings were prone to occur. The reason for this is that China's land can support a certain number of people, and agricultural production is not limited by the level of productive forces. Comparing agricultural production between the Ming and Qing dynasties, the mode of production has not changed; The only change in agricultural production is that high-yielding crops imported from the Americas, such as sweet potatoes, have been promoted in China. And it is the promotion of sweet potatoes that has created this prosperous era of Kangqian.

Sweet potato is a high-yield crop, the potato nub contains a lot of starch and a variety of vitamins, adaptable, drought-resistant, alkali-resistant, stress-resistant, warm, light and frost-resistant, is an easy to harvest crop.

Sweet potatoes were native to Central America and later spread to Luzon (present-day Philippines). Internationally, it is popular to believe that sweet potatoes were introduced to China during the Wanli period of the Ming Dynasty (1594), and the introduction was by Chen Zhenlong, a Chinese merchant who crossed the ocean.

Chen Zhenlong's ancestors are from Changle County, Fujian Province, and when he was doing business in Luzon in his early years, he discovered that there was a sweet and delicious potato in the local area, which could be eaten, so he secretly purchased its seeds. Brought back to Fuzhou, that is, tried planting on the edge of the city, and achieved unexpected success. At this time, it happened to be a major drought in central Fujian, and the grain harvest failed. Chen Zhenlong asked his son Chen Jinglun to donate sweet potatoes to Jin Xuezeng, the governor of Fujian at the time, and advocated the planting of sweet potatoes, so that the people of central Fujian survived the famine. For the future generations, a first potato pavilion was built in Fuzhou to praise the merits of Chen Zhenlong, the introducer of sweet potatoes, and Jin Xuezeng, the promoter.

By the end of the Ming Dynasty, sweet potatoes had been widely cultivated in South China and gradually spread to the north. However, due to the influence of the war in the late Ming and early Qing dynasties, the cultivation technology of sweet potatoes spread relatively slowly, and it was not until the Kangxi period that the cultivation technology of sweet potatoes spread throughout the country.

The impact of sweet potatoes on China can be understood from the following two aspects.

The area of cultivated land has expanded

According to some data, the area of arable land in the Qing Dynasty was four times that of the previous generation. Some attribute this to the Qing government's policy of persuasion. If that's the case, then we can almost conclude that before the Qing Dynasty, the Chinese were the laziest people in the world, and there was so much land that was not developed.

In this regard, we need to recognize the concept of "arable area". The cultivable area is not only related to the texture of the land itself, but also depends on the crops cultivated. And this is a sweet potato with strong adaptability, which can be cultivated in mountainous areas where rice and wheat cannot be planted, thus turning the original large tract of uncultivable land into arable land. As a result, China's arable land area has more than quadrupled.

At the same time, the cultivation of sweet potatoes, in turn, improved the soil of the land, turning the originally barren land into arable land for wheat and rice. This has increased the cultivated area of rice and wheat to a certain extent.

As an agrarian society, land is the foundation of farmers' livelihoods. Therefore, as long as there is arable land, someone will definitely grab it. The Chinese invasion of the Kanto region is a good example. For the benefit of the Manchu Eight Banners, the Qing Dynasty ordered in the seventh year of Kangxi to "recruit people and confer officials in Liaodong, and stop forever", and implemented a policy of banning the northeast. Willow trees were planted along the Shanhaiguan area, connected by ropes in the middle, and Manchurian soldiers were stationed there to strictly guard the pass, and the Han people were not allowed to leave the pass. Even if this policy did not prevent the Han people from breaking into the Kanto, "carrying the basket, helping the old and the young, or going east out of Yuguan, or crossing the Bohai Sea eastward, bees and ants gathered". Why did the Han Chinese leave their homeland and come to these barren places in the Kanto region, despite the government's pursuit? Because there is land there. Therefore, as long as there is arable land, hard-working Chinese will "grab" it, and this does not need the encouragement of those wise leaders. Therefore, regardless of the Qing government's policy of banning the Northeast and sealing the northeast, the significance of the Qing government's policy of persuasion of land reclamation on China's cultivated land is also very limited.

Increase in grain yield per acre

The introduction of sweet potatoes will not only open up new arable land. It can also be mixed and spaced with wheat, corn and other crops, which enriches the content of China's farming system, improves land utilization, and increases the yield per mu of grain.

In ancient China, there were several ways to improve land utilization, such as multiple cropping system, crop rotation and multiple cropping system, intercropping and mixed cropping system. The multiple cropping system refers to the same field harvesting two crops and three crops in one year, which has been founded in China since the Spring and Autumn Period and the Warring States Period; Crop rotation refers to the planned rotation of different crops of the farming system, in order to distinguish it from the planting of the same crop system, before the Wei and Jin dynasties, China has established a more common soybean grain rotation system; Intercropping refers to the cultivation method of sowing two crops at intervals during a certain crop growth period or replanting crops in the reserved empty row, which was initiated in China as early as the Han Dynasty; Mixed cropping refers to a cropping system in which multiple crops are sown at the same time on the same plot. Chinese farmers have long recognized the advantages of these farming systems in many ways: they can be fully profitable

Use light, heat, water and land resources to improve land utilization and productivity; A certain combination can increase the fertility of the soil and ensure the sustainability of agricultural production; A certain combination can help eliminate weeds, reduce pests and diseases, and ensure stable and high yields in agriculture.

The introduction of sweet potatoes and corn has enriched the content of multi-cropping and intercropping in China, and can not occupy the agricultural affairs of rice and corn production, and realize double and triple cropping in a piece of land.

Judging from these two characteristics of sweet potato cultivation, it is not surprising that both the cultivated area and the population increased fourfold in the Qing Dynasty. And even if there was war and famine in the middle and late Qing Dynasty, the Chinese population could be maintained at 3 to 400 million. Those who proposed the prosperous era of Kangqian also thought that the end of the Qing Dynasty was also a prosperous era. It's a pity that Chinese history has always been the history of rulers, and it has never paid attention to how the peasants were, let alone what the introduction of sweet potatoes was.

However, it should also be noted that sweet potatoes brought a prosperous population to China, but did not bring China into a strong country. Although China's population increased by 400 million, the Qing Dynasty's isolation from the country and the destruction of science and technology and culture brought China's social development to a standstill. The backwardness and beating of the Qing Dynasty was formed during this prosperous period. At the end of the Ming Dynasty, China's science and technology and economy were on a par with the West, and militarily they could also compete with the West. After this prosperous Kangqian era, China lagged far behind the West. In the eyes of Western colonizers, China was nothing more than a black Africa rich in tea during the Kangqian era.