Final answer:
Rice cultivation began around 9,000 to 6,000 years ago in the Pearl River estuary in China.
Step-by-step explanation:
Rice cultivation is believed to have begun around 9,000 to 6,000 years ago in the Pearl River estuary in what is now China. Residents of this region began cultivating rice in flooded fields called paddies. This is thought to have occurred around the same time as the rise of civilizations in Egypt and Mesopotamia. The cultivation of rice in China, along with the development of other staple crops in the Americas, played a significant role in the expansion of agriculture and the growth of human civilization.