 The Northeast Plain includes Songnen Plain in the north, Liaohe Plain in the south, and Sanjiang Plain in the northeast.The Songnen plain was formed by the Songhua and alluvial soils from the Nen.The Liaohe plain, located in the hilly areas near Changchun, was created by the separation of watersheds of the Songhua and Liaohe, which are collectively known as the Liaohe plain.