In fact Africa rice came much later:
Rice in Africa
A third domestication/hybridization appears to have happened during the African Iron Age in the Niger delta region of west Africa, by which Oryza sativa was crossed with O. barthii to produce O. glaberrima. The earliest ceramic impressions of rice grains date from between 1800 to 800 BCE in the side of Ganjigana, in northeast Nigeria. documented domesticated O. glaberrima has first been identified at Jenne-Jeno in Mali, dated between 300 BCE and 200 BCE. French plant geneticist Philippe Cubry and colleagues suggest that the domestication process may have been begun about 3,200 years ago when the Sahara was expanding and making the wild form of rice harder to find.