The Spring and Autumn Period witnessed profound reforms and changes in ancient Chinese society. Production tool improvement and technical renovation were the underlying motivation for the large-scale social reform.
The Iron Age starts from the Spring and Autumn Period Hard and sharp ironware replaced wood and stone instruments and was extensively applied in agricultural production In the Warring States Period, iron plows drawn by two oxen were used. New tools and improved plows promoted cultivation technology. However, traditional mass cultivation seriously hindered the popularization of new technology. The historical records of "slow for collective cultivation while quick for private land" reflect the profound reform of large-scale compulsory collective cultivation replaced by individual plowing. Thanks to the efficiency of iron tools and Ox-led plowing, a great deal of barren land was reclaimed in this period. The products reaped from the extra private land were no longer presented to the kings. Owners of these private lands leased their lands to peasants for collecting rent, resulting in a new production management mode, which greatly aroused the production enthusiasm of individual peasants Low-efficient, backward collective cultivation for "public fields" was strongly opposed, leading to stretches of uncultivated land with widespread weeds. The vassals, therefore, had to lease the "public fields" to peasants for cultivation, marking the collapse of the"square-fields system Landowner economy, based on land privatization and individual cultivation, rapidly expanded.
The booming landocracy intensively required to break the old system of the patriarchal nobles hereditary occupation of fiefs and military and political power, abolish their hereditary privileges in position and salary and initiate reforms aimed at developing a landocracy economy, enriching the country and forging a mighty army.
Shang Yang performed two stages of reform in the State of Qin for 20 years, making Qin gradually powerful and rich Shang Yang executed laws rigidly and cut off the nose and tattooed the face of the Prince's tutor of anyone who suborned the Prince to block the reform. When the Prince came into power, Shang Yang was torn asunder by five carts. But the laws continued and the new policies prevailed. The rapid rise of Qin in the remote western areas in the later period of the Warring States was largely attributed to the profound influence of Shang Yang's new policy. A century after the death of Shang Yang, King Ying Zheng of Qin took advantage of the influence of Shang Yang's reform that helped accelerate the pace of national unification.
Qin paid great attention to agriculture, laying a solid economic foundation for unification. The Dujiangyan Irrigation Project built by Qin's Shu County Major Li Bing is still irrigating thousands of mu of land and making the Chengdu Plain a fertile place where people no longer suffer starvation caused by drought and flood. The Zhengguo Channel, constructed in the Weihe River Plain under the leadership of Zheng Guo, irrigated 2.8 million mu of farmland, creating another enormous granary in the central Shanxi Plain.
Opening and enterprising policies and absorbing the merits of other states were important reasons for Qin's unification. In BC 238, a time shortly after King Ying Zheng of Qin came into power, the state of Han sent Zheng Guo to persuade Ying Zheng to dig a channel in the Jinghe basins to divert water for irrigation. This request was actually intended to exhaust the national strength of Qin and hinder its pace of marching eastward. But the plot failed before the channel was built. Facing the penalty, Zheng Guo said building the channel could do nothing but offer a few years more for the State of Han even though it consumed lots of fiscal revenue. But for the State of Qin, the great project would benefit later generations. Hearing this, the king of Qin changed his mind and let Zheng Guo continue its construction. However, patriarchal ministers argued that Qin's alien ministers should be dismissed since they came to Qin for persuasion and alienation. Li Si, an alien minister from Chu, submitted Remonstrance on Dispelling Alien Ministers to disprove them with the instances that the kings of Qin utilized alien ministers to build Oin. Then Ying Zheng became aware of the importance of alien ministers and cancelled the order for dispelling ministers and called Li Si back. He and other alien ministers played an active role in helping Ying Zheng unify the other six states into one country.
From BC 230 to BC 221, Ying Zheng directed his army to conquer six states and established the first centralized empire in Chinese history.
Instances of vassals contending for hegemony and progress in social reform were interwoven into the period. Collapsed ritualism and musical systems and social turmoil offered an open space for reform in states. Reform was the only way to make the country and army powerful and win the competition in the chaotic situation. Warfare for merging and seizing power was endowed with the added significance of expanding reform and new policy. On the basis of destroying the old system, the new unification made by the emerging landocracy showed the people's will and promoted the huge progress of society.