When did the walking plow first appear?

The plow was developed from a primitive double-edged triangular stone tool, called "stone plow". Xia, Shang, Western Zhou, is the initial development of China's agricultural technology, production tools and cultivation and other aspects of the greater progress and creation, the emergence of bronze agricultural tools. Spring and Autumn and Warring States period of the emergence of the iron plow, reflecting the development of China's agricultural tools in the history of major changes. Han Dynasty, produced the plow wall Han Dynasty plow is straight plow, there are double and single yamen points, basically two oxen carrying type, especially suitable for use in the plains, can ensure that the field plowed straight, relatively easy to drive, the efficiency is also higher. Wei Jin and North and South Dynasties period, agricultural production has fully entered the stage of ox-drawn plow plow, to plow - harrow - ursing for the system of intensive cultivation technology is more and more mature, straight plow structure has been quite perfect, the application of a wider range. Sui and Tang dynasties is China's ancient intensive farming agriculture expansion period, the most significant achievements of its agricultural technology is the formation of the southern paddy intensive farming technology system. The application and popularization of the curved plough greatly improved labor productivity and the quality of cultivated land. The invention of the curvilinear plow set off a new page in the history of traditional Chinese agricultural tools, which marked the development of Chinese plow into a mature stage. China's traditional walking plow has been developed to this point, and it is basically finalized in its structure. Since then, the curved shaft plow has become the mainstream plow in China. In the Song and Yuan Dynasties, the plow was based on the Tang Dynasty's curved plow, improved and perfected, shortening and bending the plow's shaft, reducing the number of parts such as the curb and the pressure digger, making the plow's body structure lighter and more flexible, and the plowing efficiency was higher. Ming and Qing dynasties, the plow has not changed much. Just to the late Qing Dynasty due to the further development of iron smelting industry, some plow plow to use iron, omit the plow arrow, digging holes in the middle of the plow tip groove, with a wooden wedge to fix the iron and regulate the depth, so that the plow structure is simplified without affecting the efficacy of the plowing, but also to make the plowing plow is more durable, not only to prolong the use of time, but also saves the cost of production, and also a kind of progress.