"Archaeological and genetic insights into the origins of domesticated rice"

Warning: the publications in my last series of posts was obtained by "cites" or "cited by", so there is a selection bias.  Not being an expert, I cannot provide the nuance and balance that might be necessary to interpret these publications.

http://www.pnas.org/content/111/17/6190.full.pdf
Archaeological and genetic insights into the origins of domesticated rice
Briana L. Gross and Zhijun Zhao

(emphasis added)
Excerpt:

India. The prehistory of indica and japonica in India presents one of the more interesting stories of domestication, long distance spread, and subsequent interactions of cultivars within a single genus of plants. Both O. rufipogon and another close wild relative, Oryza nivara, are native to India and well distributed there today, and probably were present since the Pleistocene (46). The country has a number of long archaeological sequences with good plant records including those in the Ganges River valley in the north where rice, likely wild O. rufipogon and O. nivara, is documented by 9000 BP (46,47). It is now recognized that the Indian subcontinent was probably an independent center of agricultural origins with important regions in the Ganges plain and to the south on the Deccan Plateau. Native plants that were cultivated or domesticated before crops were introduced from elsewhere include mung bean and small-seeded grasses, among others (47). The question of an origin of indica rice in India has been under active discussion, and recent research has done much to clarify and resolve the issue. It now appears that an independent origin of cultivation of ancestral indica or proto-indica rice took place in the Ganges plains, but that the plant was completely domesticated only when domesticated japonica arrived from China and hybridized with it about 4,000y ago (47). Indica consumption began early, by 8400 BP, and the plant was cultivated and appears to have been a staple food by 5000 BP (47).