There are some references about agricultural areas in China because its seems not be done at all:
North China Plain (the largest plain in China and the most important grain producing area for a long time), Guanzhong Plain and Sichuan Basin (relatively small, but still very important, Guanzhong Plain has long been the seat of China's capital in the Tang Dynasty and before; Sichuan Basin is famous for Dujiangyan Irrigation Project, a water conservancy facility that proves the richness of Sichuan Basin), the Yangtze River coastal plain (including the middle reaches and downstream areas, which is one of the richest areas, especially the Jiangnan area in the lower reaches of the Yangtze River)
View attachment 1203781
Here's a rough map of farmland, with red circles, and blue circles are the core cities
I know this is a surprising suggestion about such a huge farmland area, but considering that China has been a huge empire known for agriculture since ancient times and is renowned for various water conservancy facilities. These regions have long agricultural traditions and vast farmland areas, especially in the core areas.