Paddy Fields, Rice Terraces

During the Spring and Autumn Period (722-481 BC), two revolutionary improvements in farming technology took place. One was the use of cast iron tools and beasts of burden to pull plows, and the other was the large-scale harnessing of rivers and development of water conservation projects. The engineer Sunshu Ao of the 6th century BC and Ximen Bao of the 5th century BC are two of the oldest hydraulic engineers from China, and their works were focused upon improving irrigation systems. These developments were widely spread during the ensuing Warring States Period (403-221 BC), culminating in the enormous Du Jiang Yan Irrigation System engineered by Li Bing by 256 BC for the State of Qin in ancient Sichuan. During the Eastern Jin (317-420) and the Northern and Southern Dynasties (420-589), land-use became more intensive and efficient, rice was grown twice a year and cattle began to be used for plowing and fertilization.
It should be noted that in circa 750, 75% of China's population lived north of the river Yangtse, but by 1250, 75% of China's population lived south of the river Yangtse. Such large-scale internal migration was possible due to introduction of quick-ripening strains of rice from Vietnam suitable for multi-cropping.
Localities in China which are famous for their spectacular rice paddies are Yuanyang County, Yunnan, and Longsheng County, Guangxi.