Data expansion:
Plain (plain; Planitia (planitiae) is a large area with flat or little fluctuation on the ground, which is mainly distributed on both sides of rivers and near the ocean.
There are two kinds of plains: independent plains, which are one of the five basic land landforms in the world, such as the plains in the lower reaches of the Yangtze River. The subordinate plain is a component of a larger terrain, and the plateau can include basins (the Qinghai-Tibet Plateau includes the Qaidam Basin).
Basins often have plains and hills of different sizes, such as Guanzhong Plain, Chengdu Plain (in Sichuan Basin) and several plains in the middle reaches of the Yangtze River.
Relationship between basins and plains: Some basins include plains, hills and river valleys, such as Songliao Basin, where the plains form the northeast plains and the two lakes basins include the two lakes plains. Some large depressions in the central plain are also basins, such as Bohai-North China Basin in North China Plain, and the large depressions in Siberia Plain are Siberian Basin.
Northeast Plain, North China Plain and the middle and lower reaches of the Yangtze River are the three major plains in China, all located in the east of China and on the third step. Northeast Plain is the largest plain in China, with an altitude of about 200 meters, and fertile black soil is widely distributed.
The North China Plain is an important part of the great plains in eastern China. Most areas are below 50 meters above sea level, with convenient transportation and developed economy. Most of the plains in the middle and lower reaches of the Yangtze River are below 50 meters above sea level, with low terrain and vertical and horizontal river networks, and are known as the "water town and country".
Northeast Plain is also called Songliao Plain. Located between Daxing 'anling, Xiaoxing 'anling and Changbai Mountain. It starts from the middle reaches of Nenjiang River in the north and reaches Liaodong Bay in the south. It is about 1000 km long from north to south and about 400 km wide from east to west.
Most of them are below 200 meters above sea level, covering an area of 350,000 square kilometers, which is the largest plain in China. The Northeast Plain has thick soil, fertile land and vast cultivated land, which is the main grain producing area in China.