Genetic evidence suggests that rice was cultivated in Southeast Asia (Yangtze River Valley). See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3101000/. So, its true linguistic origin may still be something upstream.
> in any case the chinese word is mi and has no linguistic relation to the word rice
I'm not suggesting a Chinese origin of the word. But I suspect this may not be the final answer. First, the Mandarin Chinese pronunciation of the character "mi" (rice) today may not be the same as what it was pronounced 10,000 years ago. Second, people who lived in the Yangtze River Valley back then might not be speaking a Sinitic language. They might be speaking a Kra-Tai language.
> just search for how old is indian agriculture on your fave search engine
Pretty sure there were multiple origins of agriculture (e.g., Mesopotamia and Levant among others). It is difficult to argue which place came up with agriculture first.
ok but postulating chinese called it rice first and then switched to mi but rest of world kept it as rice is a stretch
rice entered europe as oryza not all that long ago and the link to tamil arici is straightforward and heavy trade existed between rome and india such that we keep finding hoards of roman era coins in india
romans were even complaining of a trade deficit with indians and emptying of their treasury
