I am not disputing that some form of wild rice was cultivated in Africa. In fact rice is a grass and grass grows everywhere. What is questionable is whether its foundation as a commercial crop began in Africa. Also, not sure where you got your information of rice in Africa 6000 years ago. Please reference this article, it says China was the origin.
Dude ease up. In your hastiness to be critical you made a transparently discoverable mistake. Adding the term "commercial" into your statement does not clarify. It is ugly dissimulation. Africa was using rice as a food crop for some thousands of years. Whether it was six or 3.5 thousand years it was a hell of a long time ago. I wrote extemporaneously, I will have to check how I came by the date but my error is not the point of discussion here. It is yours that you so egregiously defend constantly as if denigrating African history is always your aim. The reality is the world has had a few civilizations and Africa stands as one of of incomparable greatness.