Genetic evidence indicates that all varieties of paddy rice, including indica and japonica, originated from the domestication of Oryza rufipogon, a wild rice, by pre-Austronesian and Hmong-Mien-speaking cultures. This took place in present-day China, 13,500 to 8,200 years ago, south of the Yangtze River.
Model of an ancient Liangzhu city with rice paddies and a moat (3400 to 2250 BC) There are two likely centers where rice was domesticated and the wet-field technology was developed. The first is located in the lower Yangtze River and is associated with the Kuahuqiao, Hemudu, Majiabang, Songze, Liangzhu, and Maquiao cultures. It is thought to have been home to the Kra-Dai as well as the pre-Austronesians.
The second is in the middle of the Yangtze River. It is thought to have been the home of the earliest speakers of Hmong-Mien and is linked to the Pengtoushan, Nanmuyuan, Liulinxi, Daxi, Qujialing, and Shijiahe cultures. Early Austroasiatic speakers to the west and early Kra-Dai speakers to the south facilitated the spread of rice cultivation throughout southern China because of their dense population and regular trade contacts.
Sites used for rice, millet, and other crops in Neolithic China (He et al., 2017) Based on the carbon dating of rice grains and organic matter in the soil at the Chaodun site in Kunshan, the earliest paddy field found dates to 4330 BC. Archaeologists dug up paddy fields at the Neolithic Majiabang culture site of Caoxieshan. There is archaeological evidence that unhusked rice was stored for the military and buried with the deceased from the Neolithic period to the Han dynasty in China. Some archaeologists suggest that Caoxieshan dates back to between 4000 and 3000 BC.