Why does the middle and lower reaches of the Yangtze River become an oasis in China from the perspective of weather and meteorology?

China is located between the Eurasian continent and the Pacific Ocean, and there is a great difference in thermal power between land and sea. Due to the influence of horizontal pressure gradient force, the wind blows from the ocean to the land to form a monsoon, which brings a lot of water vapor. Due to the influence of the Pacific subtropical high, the temperature in China is high, and water vapor can quickly evaporate and condense into small water droplets, bringing a lot of precipitation. The environment where plants grow is full of water, the temperature is suitable, the plants grow vigorously, and gradually develop into oases.