<P> From East Asia, rice was spread to Southeast and South Asia . Rice was introduced to Europe through Western Asia, and to the Americas through European colonization . </P> <P> There have been many debates on the origins of the domesticated rice . Genetic evidence published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) shows that all forms of Asian rice, both indica and japonica, spring from a single domestication that occurred 8,200--13,500 years ago in China of the wild rice Oryza rufipogon . A 2012 study published in Nature, through a map of rice genome variation, indicated that the domestication of rice occurred in the Pearl River valley region of China based on the genetic evidence . From East Asia, rice was spread to South and Southeast Asia . Before this research, the commonly accepted view, based on archaeological evidence, is that rice was first domesticated in the region of the Yangtze River valley in China . </P> <P> Morphological studies of rice phytoliths from the Diaotonghuan archaeological site clearly show the transition from the collection of wild rice to the cultivation of domesticated rice . The large number of wild rice phytoliths at the Diaotonghuan level dating from 12,000--11,000 BP indicates that wild rice collection was part of the local means of subsistence . Changes in the morphology of Diaotonghuan phytoliths dating from 10,000--8,000 BP show that rice had by this time been domesticated . Soon afterwards the two major varieties of indica and japonica rice were being grown in Central China . In the late 3rd millennium BC, there was a rapid expansion of rice cultivation into mainland Southeast Asia and westwards across India and Nepal . </P> <P> In 2003, Korean archaeologists claimed to have discovered the world's oldest domesticated rice . Their 15,000 - year - old age challenges the accepted view that rice cultivation originated in China about 12,000 years ago . These findings were received by academia with strong skepticism, and the results and their publicizing has been cited as being driven by a combination of nationalist and regional interests . In 2011, a combined effort by the Stanford University, New York University, Washington University in St. Louis, and Purdue University has provided the strongest evidence yet that there is only one single origin of domesticated rice, in the Yangtze Valley of China . </P>

Where does the uk get its rice from